Child Play Activity Modeling for Playground Space Design Using the Context-Based Activity Modeling Method

Abstract

Extensive attention has been given to children’s play spaces in public environments. Still, there exists a research need to devise a more comprehensive and structured design framework for space design addressing more comprehensive and structured activity modeling capabilities. The Context-Based Activity Modeling (CBAM) has been proposed as a framework for service design where activities are represented by elements like action verb, actors, object, tool, and contexts, where context is further represented by goal, relevant structure, physical, and psychological contexts. In this paper, children’s play activities such as throw, run, chase, hide, seek, and seize as observed in a community courtyard setting have been represented and interrogated using the CBAM method. Then, six specific design strategies have been derived for enhancing children’s play space design. As demonstrated in this way, CBAM is proposed as a framework for activity-centered space design for child playground. Experiential sustainability of children’s play activities are supported by play space design fully addressing detailed context elements of CBAM.

1. Introduction

1.1. Children’s Activity and Playground Design

With urban modernization and evolving community spatial configurations, children’s activity spaces have received growing scholarly attention. The environment plays a pivotal role in child development, significantly influencing the acquisition of perceptual abilities and developmental experiences. Well-designed outdoor environments facilitate sensory-motor skill development, cognitive understanding of the world, enhanced social interaction capabilities and moral and personality development [1].

Contemporary urban children’s activities have undergone substantial transformation. Community spaces, as the principal venues for such activities, now exhibit heightened diversity in both activity modalities and spatial utilization requirements. However, there is a contradiction between the patterned design of existing children’s spaces and the diversity of children’s behavioral patterns, and it is urgently needed to develop innovative design approaches for spatial environments that better accommodate and reflect the dynamic nature of children’s activities.

The development goals of children at each stage of growth are multifaceted, encompassing physiological, cognitive, social, and emotional developmental dimensions [2]. Also, their activity needs are multifaceted. Distinct age groups exhibit varying activity preferences and behavioral characteristics [3]. For example, children aged 3 to 5 tend to engage in simpler, equipment-assisted activities, often in seated or stationary play. Children aged 6 to 8 are more active and energetic, while children aged 9 to 12, at a critical stage of cognitive growth, show a pronounced preference for intellectually stimulating games, such as puzzles [3]. These differences present new requirements for space design. Through qualitative research, this study focuses on children aged 6 to 12 within urban community spaces, as they are at a crucial stage of growth and cognitive development.

Many children’s space design paradigms fail to incorporate child-centered perspectives [4]. While these designs meticulously address visual aesthetics, safety standards, and proportional scaling, they often disregard children’s intrinsic activity patterns and spatial autonomy. This fundamental disconnect stems from insufficient systematic observation of the actual system for children’s real activities, resulting in spaces that prioritize exhibiting formal diversity over providing adequate behavioral support. Consequently, children are relegated to passive users rather than active participants, ultimately compromising the spaces’ engagement potential and developmental value.

In contrast, game places with greater isolation from the outside world (e.g., formal play venues) often fail to fully meet children’s needs. Studies indicate that children show stronger preferences for informal play spaces like streets [5]. These include non-dedicated public areas such as neighborhood street sections, leisure streets, and commuting routes, which were not originally designed for play [6], in which children consistently demonstrate more vigorous physical activity, spontaneous exploration, and self-directed play activities. These organic usage patterns in informal spaces reveal a striking contrast to those in conventional play areas, offering more authentic insights into children’s genuine spatial preferences and needs. This study, based on continuous observations and recordings of children’s activity behaviors in a community courtyard space, aims to rethink and reconstruct the design strategies for children’s activity spaces from a behavioral perspective [7].

1.2. The Need for a Structured Approach to Space Design

Despite extensive scholarly attention to children’s activity spaces in public environments, the gap between children’s activity and spatial response remains significant. Children’s activities are characterized by immediacy, playfulness, and high situational dependence, especially in open spaces where children are more likely to engage in spontaneous creativity, rule modification, and group collaboration [8]. In the basic principles of public space design, theories on human–environment interaction are particularly valuable for children’s space design [9]. The Urban Open Space Design Guidelines, for instance, advocate for developmentally appropriate environments that balance safety, comfort, and aesthetic quality, yet their application frequently reduces complex behavioral needs to oversimplified activity zones [9]. This conventional approach, dominated by functional partitioning and visual considerations, lacks the necessary analytical framework to examine nuanced behavior-environment relationships. Without a structured observational framework, design could fall into simplistic zoning of “functional areas”. Relying solely on functional and visual considerations results in a lack of in-depth analysis of the relationship between behavior and environment, making it difficult for the design to respond to the complex and changing needs of children’s space use.

While existing studies have established preliminary links between children’s activity and spatial response, there remains a lack of a structured framework for children’s activity in space design methodologies. In research on space design based on children’s activities, a literature review integrating studies on urban green spaces, child-friendly cities, and children’s infrastructure has introduced the concept of Children’s Green Infrastructure (CGI), emphasizing the need for designs that are more equitable, inclusive, and participatory [10]. In the practice of outdoor space design, integrating narrative construction into spatial design has also been proposed to create better child-friendly community outdoor spaces [11]. Additionally, research on kindergarten environments has highlighted three key dimensions of interaction in children’s space design: interactions between people, between people and objects, and between people and the environment [12].

Building upon cognitive psychology frameworks, researchers have systematically classified children’s developmental needs across various age groups [13], enabling the creation of tailored environments that respond to their evolving psychological and behavioral characteristics. This theoretical advancement enables the creation of age-specific environments: preschool spaces that foster exploration and sensory interaction, contrasted with adolescent spaces designed to accommodate emerging social needs and privacy requirements [14]. A study characterizes these realms as advocacy, romantic, needs, learning, rights, institutionalization, and proactive. By proposing a seventh, proactive realm, this acts as a more integrative and effective way to involve children in design and planning [15]. Moreover, the integration of design thinking principles has further advanced the methodology of children’s space design, incorporating tools such as visualization, user co-creation strategies, and prototyping into children’s space research. These developments collectively represent a paradigm shift from normative, adult-centric design models to evidence-based frameworks that recognize children as active agents in shaping their environments.

Note that children’s space design methodologies have profound connection with their behavior, development, and social interactions. When designing for children, it should differ from conventional functional space design and require a multidisciplinary approach, incorporating psychology, safety, and developmental theories, and closely aligning with design theory.

While existing research provides valuable foundational knowledge, it reveals a crucial methodological gap: the absence of a comprehensive system for analyzing and implementing the dynamic interrelationships between activity patterns and environmental features. Given the complexity of children’s activities, relying solely on designers’ subjective experience or case study comparisons is no longer sufficient to systematically capture children’s behavioral sequences, spatial preferences, and potential goals in space. Therefore, child-centric space design requires a structured and systematic analytical approach, necessitating standardized observational methods and theoretical models to guide the entire design process from initial analysis to implementation.

Many of space design models focus on the structure and the function of space design [16], but not on activities for which the space is provided. As a notable previous work on the structured mapping of activity and space of a building, Simoff and Maher [16] proposed an Activity–Space Ontology. With hierarchical representations of activity and space elements, the Activity–Space ontology makes explicit representation of the activities and resulting spatial arrangement and, to some extent, some supporting structure like equipment in an architectural design. Specifically, an activity is represented by performer, consumer, equipment, service, time, and constraints, while a space is represented by geometry, divider, link, and constraints [16]. For example, a space acting as a hospital bedroom would require an appropriate spatial layout and set of equipment for activities like laying, sleeping, reading, and eating as well as getting in and out. Objects like bed and movable table are those associated equipment; a bed for laying, sleeping and moving in and out and a movable table for reading and eating, respectively [16]. Some efforts toward automatic mapping of activity and space have also been made [17,18]. Note that space elements go down to a room level with some equipment needed to perform functions. However, this ontology does not address more detailed relations among activity and context elements. Nor actor experience evaluation can be accommodated. Thus, this cannot support required level of space design suggestions and strategy to address psychological issues and diverse value elucidations. The activity level can also be limited to a task level rather than detailed activity level. Therefore, there exists research needs to devise a more comprehensive and structured design framework for space design addressing more comprehensive and structured activity modeling capabilities.

1.3. Context-Based Activity Modeling as a Design Framework

Context-Based Activity Modeling (CBAM) is a schematic framework that structures the relationship between human activity and contexts [19,20]. Initially devised for service design [19,20], CBAM has since been extended to various design applications, including design for affordances [21], representation of design processes [22], emotional experience and experience data representation [23], cognitive exercises for design thinking [24]. The core of the CBAM method emphasizes that all activities are critically influenced by contexts and context information must be specified in a structured and comprehensive manner.

The basic part of the activity description is the action verb. The object of the action is the object of the activity. Three different actors are involved; the activity is conducted by the active actor. In some cases, the activity may have the passive actor and/or the third-party actor as well. The tool can be used in conducting the activity and is specified if needed. The object and the tool are further described with their properties. The activity description is completed with context elements. The context is described by four types of context elements. The goal context represents the objective of the activity. It can be represented by another activity for which the present activity is conducted, often beforehand. Sometimes, the goal may also represent values the present activity is to pursue. The relevant structures include structural entities related with the object and the tool in performing the activity. The physical context includes time, place, and other various environmental information such as lighting condition and weather condition. Note that the physical context information can be obtained from various sensors. The psychological context has been expanded from the initial social context of an ISO definition [25] of contexts to represent diverse emotional experiences of the active actor. Actor emotion experiences could be represented with actor subjective evaluations as in the case of [26] or with observer evaluations. The social context represents whether the activity is conducted in public or in private. Also, whether the activity is conducted alone or together with other actors can be represented. Note that the CBAM method has been made by combining the activity theory [27] and the ISO definition of contexts [25] with some extension to address psychological contexts.

That is, the activity is described such that “the active actor conducts the action of the action verb on the object using the tool (to the passive actor) under the context composed of the goal, the relevant structure, the physical context and the psychological context elements” [20]. Understanding the relationship between these context elements and observable activity sequences is a key to understanding spatial activities and formulating effective design strategies. Note that rich context information represented in the CBAM method is a significant advantage of CBAM over the Activity–Space ontology. While equipment element is the only structure element is the Activity–Space ontology’s activity representation, objects, tools, and relevant structures all can address space structural elements in CBAM. This also makes CBAM much more powerful in representing diverse various space structural elements tightly associated with a corresponding activity.

Children often experience space in a passive role [10], whereas CBAM, as an active design thinking framework, adopts an active design thinking approach. Through the dissection of context, CBAM integrates an activity-based analytical system that helps transform passivity into proactivity. This approach allows for the re-examination, rethinking, and formulation of more structured design strategies from the child’s perspective as children actors experiences including emotional experiences are reflected. By focusing on the essence of activities and behaviors, CBAM reshapes the design thinking of children’s spaces.

Moreover, when applied to the analysis of children’s activities, CBAM effectively connects the environment with activity and goal, assisting designers in preemptively modeling behaviors, dissecting action sequences, and predicting spatial strategies. According to CBAM principles, the analysis of activities is divided into various components: actors, objects, tools, and contexts. This model functions similarly to a syntax analysis of activities, extracting the details of children’s activities with children themselves acting as the actors. Within the CBAM framework, children, as the central agents of the activity, interpret the spatial structures related to their actions. After decomposing these actions, the underlying spatial elements become more visible and easier to understand.

The objective of the research in this paper is to propose the CBAM method as a framework to design child playground space structures so that diverse children play activities and their associated space structural elements can be systematically associated. Based on the activity modeling framework of CBAM, this study selects a community space with high-frequency children’s activities for analysis. By observing and recording children’s activities in this space and applying the CBAM model, the study analyzes how spatial elements (such as covering structures, flooring, and boundaries) influence behaviors for specific activities. The findings provide design recommendations for children’s activity space based on these findings.

In this paper, the CBAM method is used to describe children play activities in detail with actor, object, tool as well as goal context, relevant structure, physical context, and psychological context including experience evaluation of the active actor, that is, a child actively and dynamically engaged in playing. A typical play game using sandbags in a community space, which is not particularly designed for children play activities, is used to explain how the CBAM method of modeling activities can support space design. By modeling in detail key play activities of the play game, how specific activities of playing children are influenced by objects, tools, relevant structures, and physical context are systematically understood. Then, design suggestions and strategies are derived from such activity modeling. Discussions on the role of the CBAM method as a framework of space design, by specifically relating activities, are provided together with the contributions of research of the paper. Then the paper is concluded with remarks on future work.

2. Children Play Activities Represented Using the CBAM Method

The space selected by this study, if physically limited, accommodates children’s rich interaction and diverse psychological states. They have many spontaneous games and behaviors in this activity venue. Based on the research framework of the CBAM method, design practice needs to pay more attention to the detailed and direct relationship between actors, activities and environments. We need to observe more detailed activities and low-level actions. Therefore, this study pays great attention to the detailed activities in what is called the sandbag game and analyzes it in detail.

The rules of the sandbag game are relatively simple. How the game is played is illustrated in Figure 1. To begin with, children are divided into two groups: one group is responsible for throwing sandbags, while the other group must avoid them. The throwing group is further divided into two subgroups positioned at opposite ends of the field, while the avoiding group stands in the center. Then, the two throwing groups take turns aiming at the children in the middle, while the children in the center must actively run in order to avoid being hit by the sandbags. When a child is hit by a sandbag, the thrower is allowed to chase after them. The child who is hit may choose to either continue being chased or try to hide. If the thrower successfully finds and tags the child within a limited amount of time, the child is considered “out” and will switch to the throwing group in the next round. The reason why the sandbag game is chosen is that with relatively simple set of activities the whole game can be clearly explained so that the interrelations among these activities can be easily understood while excitement and playfulness of game play is high.

The main forms of activities in this game are throw, run, chase, hide, seek, and seize. These activities form a sequence of throwing sandbags as shown in Figure 2, creating an interesting spontaneity in the designed game environment, which was not particularly designed for the game. This study analyzes this series of activities in detail through the CBAM method so that structured and sustained space design suggestions can be made. Each of these activities is now explained in this section through the CBAM descriptions. Note that the explanations focus more on context elements such as relevant structure and physical and psychological contexts as they are critical for play space design.

2.1. Throw

2.1.1. Actors

Throwing the sandbag is the core interactive activity in the sandbag game. The throw activity marks the beginning of a series of activities where a child, using his or her hand as a tool, throws the sandbag toward a selected target within the opposing group.

This activity involves the coordination of the active actor thrower, the passive actor target child and third-party actor observers. The CBAM description of throw activity is shown in Figure 3 together with a supporting illustration. Meanwhile, elderly people who take care of children and passersby present as third-party actors in the activity supervise the game to ensure the safety of the children. A child throws the sandbag with his hand as the tool to a target child under the context described in detail by the context element. As a thrower, the small size of the child’s hand affects how they grip and throw the sandbag, which is soft and light. Note these properties of the object and the tool are described as parts of the descriptions of the object and the tool, respectively, as shown in Figure 3. From CBAM description of the activity throw, the goal context of the throwing activity is to have fun, to play the sandbag game, and to hit target child.

2.1.2. Relevant Structure

Within architectural spatial design, the relevant structure context elements in the context are particularly significant. The playing space is limited, and the covering structures are closely related to the throwing activity. In addition, because the game takes place in an open yet constrained community courtyard, the physical structures within the site (such as variations in terrain and obstructive vegetation) become key factors influencing the throwing strategy.

The boundary of the activity is implicitly defined, often relying on surrounding net-like structures, gaps in the ground, or tile counts as reference points. However, these boundary elements remain ambiguous, which may introduce certain safety risks to the activity in the case of this particular community courtyard in contrast to other sandbag game situations, such as at school, where the boundary is explicitly defined.

2.1.3. Physical Context and Psychological Context

Additionally, the physical context that influences throwing activity includes location, landscape, time, weather and temperature. Environmental variables also impact the throwing activity. The activity takes place in the community square at night, with clear weather and temperatures ranging from 26 to 28 °C. Note that the time is at night as shown in Figure 3. Low visibility at night may increase the difficulty for targets to evade, while light windy conditions may alter the trajectory of the sandbag. Furthermore, psychological context plays a crucial role. The thrower is often in a state of high motivation and excitement, which may lead to more aggressive throwing patterns. Since the game is played in a public social setting, feedback from spectators may influence the thrower’s decision-making process.

Overall, throwing the sandbag is an interactive process influenced by spatial constraints, physical characteristics, social context, and psychological motivation. A deeper analysis of this activity within the fields of play space design, interaction design, and game research can provide insights into how children engage in target judgment, strategic decision-making, and social interaction within dynamic environments, providing structured foundations for playground design, game design, child activity research, and safety interventions.

2.2. Run

The CBAM description of the activity of a child running in the community courtyard environment activity is shown together with an illustrative photo in Figure 4 of Run. It describes the activity element of running, including actors, tools, goal context, relevant structure, physical context, and psychological context.

2.2.1. Actors

In this activity, the active actor is the running child who performs the action. Other children, who may be opponents in the sandbag game, are the third-party actors. The elderly people who care for the children and passersby who may have a potential impact on the safety of the children are also the third-party actors of this activity. The tool used in the activity is light-weight shoes, which helps improve running speed and agility. The friction structure of the shoe sole is an important property of the shoes that helps prevent falls.

The goal context of the running activity can be divided into four categories: To have fun: gaining enjoyment from the game; To improve speed and endurance: such as racing or athletic training; To escape and hide somewhere: common in hide-and-seek or chase games, where it is an important strategy for avoiding others. In the sandbag game, to chase the target child is also a goal context.

2.2.2. Relevant Structure

• When a child runs, the relevant structures around him affect his activity. These include play space, covering structure, boundary line, ground paving, and pathway structure.
• Play Space: Limited space may cause collisions or intense competition in specific areas.
• Covering Structure: Other physical structures such as low shrubs and benches can add fun (e.g., obstacle courses) or become obstacles in the running route.
• Boundary Line: Implicit boundaries, such as those implicitly defined shrubs, fences, or road edges, limit the running area and can pose a potential risk for collisions.
• Ground Paving: The current hard cement surface increases the risk of falling, and the material of the ground directly impacts the safety and speed control during running. Falls may lead to abrasions or injuries.
• Pathway Structure: Enclosed or straight pathways help children run in a more orderly manner, reducing the risk of collisions due to chaotic running.

2.2.3. Physical Context and Psychological Context

The physical context plays a crucial role in influencing running activity. The activity takes place in the community square. The surrounding landscape consists of unevenly distributed shrubs, which can obstruct the view and create natural barriers along the running path. The running activity is performed at night, with clear weather and temperatures ranging from 26 to 28 °C, which are generally favorable for physical activities. However, the lower visibility at night may compromise safety, as it limits the child’s ability to see obstacles or other individuals in the area. Therefore, light should be added to the physical context.

In terms of the psychological context, the CBAM description emphasizes the mental state of the child while running. The occupant context of low pedestrian traffic is favorable, providing the runners with ample space for movement. Given that the activity is held in a public space with strong social attributes, external factors may influence the child’s activity. Typically, the child exhibits high levels of excitement and happiness while running, contributing to a high motivation level. Despite this, the safety index is only rated 4 out of 10, indicating that the running activity carries inherent risks, including potential falls, collisions, or accidental injuries. Note that running activities are at both delight points and pain points. Certainly, space design suggestions could be made based on the CBAM description.

2.3. Chase

2.3.1. Actors

In the CBAM description of the activity chase shown in Figure 5 with an illustrative photo, different actors play distinct roles that influence the activity: The child who is chasing and actively participating in the game is the active actor. The target child, who is being chased, is the passive actor. Apart from those, elderly people who take care of the children and passersby serve as the third-party actors. They are not directly involved in the game but may influence its safety and the way the children play the game.

The object is the target child hit by the sandbag, indicating the nature of the sandbag game. The goals of the chase activity can be categorized into three types: Firstly, to have fun: Children engage in the game for enjoyment and social interaction. Secondly, to play sandbag game: The game may revolve around the throwing and dodging of sandbags. Thirdly, to capture and win the game: The game has a competitive nature, where players may need to strategically dodge or hit opponents to win.

2.3.2. Relevant Structure

The physical environment and surrounding structures influence children’s activity and safety during the chase:

• Play Space: The play area is limited, suggesting that the available space may lead to increased risks of collisions between participants.
• Covering Structure: Other physical structures, like low shrubs and benches, can add fun elements but may also serve as potential obstacles, affecting the activity.
• Boundary Line: Implicit boundaries, such as those implicitly defined by shrubs, fences, or road edges, may limit the chasing area, affecting the game’s organization and creating potential collision hazards.
• Ground Paving: The hard cement surface increases the risk of injury in case of a fall, potentially leading to abrasions or fractures.
• Pathway Structure: Enclosed pathways help children chase in a more orderly manner, reducing the risk of slipping down.

2.3.3. Physical Context and Psychological Context

The location, landscape, time, and temperature of the environment impact the chase activity as in the activity of running. Notably, the landscape includes tall and low shrubs, which may affect visibility and influence the chasing route. The game is more likely to occur at night, when insufficient lighting may reduce visibility, increasing the risk of accidents.

In terms of the psychological context, occupancy in crowded environments indicates a higher number of people present, which may increase the risk of collisions during the game. Additionally, since the game takes place in a public space, it is susceptible to external distractions that could affect actors’ focus and activity. The children’s emotions are excited and focused during the chase, as they are usually full of energy and highly engaged in the game. The motivation is high as participants are keenly interested in the game and have a strong desire to compete. The safety score is 4 out of 10, indicating that there are potential safety risks due to factors like hard ground, limited space and poor lighting, which may lead to falling, collisions, or injuries.

2.4. Hide

2.4.1. Actors

As illustrated in Figure 6, the hide activity involves a child as the active actor (i.e., the hider), who simultaneously serves as the target child in the subsequent seek activity. He needs to find a suitable hiding spot and avoid being discovered. The third-party actors include elderly people who take care of the children and passersby. The object of the activity is the body of the child. Note that the body of the child is small in shape and with short height. The tool is hiding structure. Note that the sizes of the body and the hiding structure are highly related. The goal context of the hide activity mainly includes: to play games, to stay hidden and avoid detection and to observe the seeker’s movements in order to not be found.

2.4.2. Relevant Structure

The physical environment and surrounding structures influence children’s activity and safety during the chase:

• Play Space: The play area is limited.
• Covering Structure: Other physical structures, like low shrubs and benches, can add fun elements that can be used for hiding structure. This is a key relevant structure of the activity of hiding.
• Boundary Line: Implicit boundaries implicitly defined by those such as shrubs, fences, or road edge, which may limit the area where the appropriate covering structure can be found.
• Ground Paving: The ground is made of hard cement.

2.4.3. Physical Context and Psychological Context

The physical context, including location, landscape, time and temperature, is similar to the activities of run and throw. Specifically, the tall and low shrubs in the community courtyard may help in identifying a proper hiding structure that is to be chosen from covering structures, so that ideal hiding spots can be identified. Note that relative sizes of covering structures with the body would be critical. At night, the low lighting condition helps the hiders stay concealed, but it may also pose a risk to safety. The clear, slight windy weather is perfect for outdoor activities and does not interfere with the game’s progress. The warm and comfortable temperature allows for prolonged hiding without discomfort.

In terms of the psychological context, the occupant is crowded, which may increase external distractions, such as the influence of passersby or other players. The game takes place in a public space, meaning it could be affected by external environmental factors. Emotionally, children usually feel excited and tense while hiding. They are thrilled by the game but may also feel nervous about being found. The motivation behind the activity is competitive as the child needs to develop strategies and fully utilize the environment to increase their chances of winning. In terms of safety, the rating is 6 out of 10. Compared to chase games, the safety in hide-and-seek is higher, but there are still risks, such as collisions with obstacles, discomfort from crouching for long periods, or accidents due to the low lighting condition in the environment.

2.5. Seek

2.5.1. Actors

The seek activity happens in tight interaction with the hide activity. After the children have been hidden, a child is tasked with finding the targeted child within a certain time limit. In this seek activity shown in Figure 7, the active actor is a child who is seeking, as the main executor of the seek activity. Their primary task is to pursue and locate the target child in the game. The third-party actors still include the elderly people who take care of children and passersby, who may supervise or unintentionally interfere.

The object of the activity is the target child hit by the sandbag. Apart from that, the actor uses shoes as a tool. The goal context of the seeking activity includes the following: to have fun, to play games, and to find the hidden target child.

2.5.2. Relevant Structure

• Play Space: The play area is limited, which may intensify competition and restrict the area of seeking the target child.
• Covering Structures: Includes low shrubs and other objects that both enrich the game and present visual obstructions to finding the target child.
• Boundary Line: Implicit boundaries, implicitly defined by other structure elements such as low shrubs and benches and may limit the area where the target child hides the body using various structures of covering structure.
• Ground Paving: The ground is made of hard cement.
• Note that seeking the target child is relevant to covering structure in the limited play space as the boundary line implicitly defines the area of seeking.

2.5.3. Physical Context and Psychological Context

The physical environment is open and suitable for outdoor activities. The activity takes place at night, with low lighting condition that may affect the actors’ visibility. The landscape of the area is made up of tall and low shrubs, which affect the range of sight and increase the potential difficulty during the search.

In terms of the psychological environment, the child is typically in a state of excitement and happiness, with high motivation to actively participate in the game. The game also has strong social attributes. However, because the activity occurs at night, the safety rating is lower due to potential hazards. Despite favorable weather conditions, the reduced visibility and limited space could increase the risk of falls, collisions and other accidents. Therefore, the safety rating is 4 out of 10, with a moderate level of difficulty.

2.6. Seize

2.6.1. Actors

The seize activity occurs after the target child is identified and the CBAM description of the activity Seize is shown in Figure 8. A child uses his or her hand to grab the target child in order to win the game. The active actor is the child who seizes the target, performing the action of grabbing the target child with his or her hand. The passive actor is the target child, who is the one being seized. They may attempt to escape or, once caught, may stop moving. During the process of being seized, the target child must try to avoid being completely controlled. The third-party actors include the elderly caregivers and passersby who may observe or affect the game indirectly.

The object is the target child’s body, which is soft and fragile, requiring careful handling during the seizing process to avoid injury. It also signifies that the activity involves seizing the target and stopping his movement. The tool used in this activity is the hand, which is small in size.

In the seize activity, the goal context primarily focuses on the following aspects:

To stop the movement of the target child; To play sandbag game—Engage in the sandbag game where the activity of seizing plays a central role; To capture and win the game: Once the target is captured, the game ends then a new round may begin.

2.6.2. Relevant Structure

• Play Space: The limited play space means the area in which the game occurs is constrained, increasing the chances of collisions and difficulty in controlling the target.
• Covering Structures: Environmental structure elements like low shrubs and benches become obstacles during the seizing process, potentially interfering with the smooth execution of the activity.
• Boundary Line: The implicit boundary—there is no clearly defined area, which could affect the seizing range and affect the difficulty of the activity.
• Clothes of Hit Child: Seizing the target child’s clothes may be easier than directly seizing the child’s body because the clothes are softer and provide some grab-ability affordance [17]. In this way, the risk of harm from direct contact can be avoided.

In this activity, the target child’s clothing may sometimes be grabbed instead of his or her body or limbs. Seizing the clothing reduces the potential for harm to the child’s body compared to directly seizing the child’s body.

2.6.3. Physical Context and Psychological Context

In the physical context, elements such as tall and low shrubs and other environmental features can affect the visibility of the target child, presenting challenges or providing cover during the seizing activity. Nighttime conditions can not only increase the difficulty of the activity but also add to the excitement of the game. The crowded nature of the space, with many children participating, could increase the risk of collisions during the seizing process, making the activity more complex and engaging. As the activity takes place in a public space, external distractions and bystander attention may influence the child’s focus and concentration levels.

The child demonstrates an excited and happy emotional state characterized by high energy and visible enjoyment during target–seize sequences. His motivation is high, evidenced by full commitment to game objectives and active competition participation. The activity safety rating is 6 out of 10, indicating that while the space is suitable for play, there is still a risk of falling, collisions, or injury due to the force involved in the seizing activity. The difficulty rating is 7 out of 10, as capturing the target requires certain skills and speed and the limitations of the space, along with the target child’s agility, further increase the challenge.

3. Strategies for Children Playground Design

This study based on the CBAM method interrogated children’s play activities such as throw, run, chase, hide, seek, and seize as observed in a community courtyard setting. Through the identification of activity context elements, it is found that children’s play activities are highly dependent on physical structures of the relevant structure context, including covering structures, ground surface materials, pathway layout, spatial boundaries as well as visual organization. These structures serve not only as mediating elements that trigger activity but also play a crucial role in enhancing safety and emotional experiences and fostering a sense of engagement. Based on the CBAM approach, six specific design strategies are proposed in this paper for enhancing outdoor children’s play environments.

3.1. Improve Ground Surface Materials and Impact Buffering

The quality of ground surfaces is a critical factor that affects children throughout various play activities as clearly shown in the relevant structure of ground paving in four activities of six activities of the sandbag play. See Figure 4, Figure 5, Figure 6 and Figure 7. In particular, during high-speed activities such as running and chasing, hard surfaces pose considerable safety risks as reflected in the psychological context element of safety level 4 out of 10 in the CBAM description of run and chase activities. Thus, clear space design suggestions can be made as follows.

To address this, ground materials should be selected based on their elasticity, anti-slip properties, and surface friction. Suitable options include rubber granules, turf, or foam mats, which provide cushioning and reduce impact from falls. Materials such as silicone, plastic flooring, carpet, grass, EVA foam, or sand are recommended for creating soft and responsive surfaces.

Extending from the clear space design suggestion of the ground paving improvement, an additional space design suggestion can be advisable to implement impact-buffering zones or soft wrapping treatments near turning points and obstacle edges to reduce the likelihood of collision-related injuries. Beyond safety, aesthetic and experiential factors should also be considered. Designers may incorporate colorful surface patterns and gentle undulations or micro-topographies to enrich the sensory experience and enhance the fun of activities such as running and dodging. These strategies help create a safe play environment, engaging and stimulating, encouraging greater participation and physical exploration among children.

3.2. Balance Visibility and Visual Obstruction

As shown in the tool element and the covering structure of the relevant structure in the CBAM analysis of the activity of hide in Figure 6, purposeful visual obstruction can be a key factor in enriching gameplay. Designers are encouraged to incorporate soft-edged, flexible, and visually integrated structural elements into children’s play spaces. Examples include semi-transparent or spaced materials, such as perforated walls, trellises, or wooden slats. These provide sufficient concealment while still allowing for partial visual contact, ensuring a balance between immersion and safety.

In addition, a variety of covering structures should be integrated across the play area. According to CBAM, children’s body size, height, and hiding preferences significantly influence the form and scale of such structures. Recommended elements include low shrubs, vertical columns, curved walls, and recessed platforms. These forms not only provide hiding opportunities but also enhance spatial richness, playfulness, and strategic variation in the environment.

In contrast, some visibility should be ensured for safety. In activities such as hide-and-seek or sandbag throwing, children often rely on surrounding physical elements for concealment or tactical movement. Therefore, visibility and obstruction must be carefully balanced in design.

On the one hand, visibility along circulation paths—particularly those frequently used for running or chasing—should be optimized according to children’s height and eye-level perspectives. Designers should consider the child’s visual field by adopting a lower vantage point. This may include the removal or repositioning of obstacles that block sightlines at child height, such as trash bins, stone stools, or low-hanging branches. Enhancing visual accessibility in key movement zones supports both safety and navigation.

3.3. Define Explicit and Implicit Boundaries in Play Spaces

In the context of play activities of the sandbag game in a community courtyard, boundary lines emerge as a frequently referenced relevant structure within the CBAM framework. These boundaries are often implicit—children tend to define their spatial limits using elements such as floor tile patterns, vegetation lines, safety nets, or the edges of walls. This ambiguity has a dual effect on children’s activities. On the one hand, undefined boundaries allow for flexible rule-making and self-directed spatial organization, thereby enhancing the imaginative and playful nature of activities. On the other hand, unclear boundaries may blur the line between third-party participants and active actors, increasing the randomness and unpredictability of movement, which could lead to safety concerns.

In design practice, boundaries in children’s play areas should be tailored to the site’s characteristics and the behavioral needs of the children. Rather than relying on rigid fences or painted lines, it is more effective to create flexible, engaging, and safety-conscious “activity boundaries”. These can be achieved through the use of contrasting materials, guiding lights, or discreet markers, all of which can help make boundaries more perceptible. Such design strategies both support imaginative play and enhance spatial legibility and safety, facilitating a better-organized and more secure play environment.

3.4. Integrate Clothing into the Activity Support System

Note that the clothes of playing children appears as a relevant structure in the activity of seize as shown in Figure 8. Through the activity modeling framework of CBAM, it is noted that children’s clothing in the game not only carries the function of wearing but also acts as an important physical medium in seizing.

Note that, by comparing judo with sumo and other structured games, it can be seen that different types of clothing structures (such as looseness, friction, color, and feedback mechanisms) directly affect game strategies and interaction forms. The players in judo wear loose, color-uniform clothing, with a prominent belt around their waist. In judo competitions, shown in Figure 9, athletes are only permitted to grip their opponents by the uniform (jacket) and belt. In contrast, in sumo wrestling, competitors wear minimal clothing and while they engage in full-body contact to lift or displace each other, pinching or grasping the skin is not allowed. In such a context, loose clothing can interfere with precise physical maneuvers, causing unintended friction or misplaced grips.

From the perspective of the relevant structure context of the CBAM framework, the design of sport-related clothing must carefully consider how physical garments affect movement strategies and techniques. The thick material and loose structure of judo uniforms are intentionally designed to provide grip points, enabling players to execute throws, holds, and defensive moves by leveraging the clothing itself. This structural feature directly influences the tactical dynamics of the sport. On the other hand, the mawashi (loincloth) worn in sumo minimizes external grip points, thereby shifting the competition focus toward direct body-to-body engagement and balance control. This distinction in clothing structure not only shapes the nature of physical contact but also fundamentally defines the stylistic identity of the respective sports.

Therefore, it is recommended that clothing be considered as an important relevant structure of play activities. High-friction and safe materials should be applied to areas that are frequently grasped during gameplay. Camouflage tones or high-visibility colors can be strategically used to support different activity goals—such as hiding versus chasing. Additionally, interactive feedback mechanisms, such as garments that emit light or sound when triggered, could further enrich the play experience. In this way, the relevant structures of the clothing of play activities could provide significant roles in game activity and experience design.

Importantly, clothing design should be coordinated with spatial covering structures to create strategic interactions between the body and the environment. These design strategies collectively contribute to enhancing the impassiveness, safety, and systemic coherence of play, fostering a dynamic integration of body, medium, and space in the children’s activity ecosystem. These critical design considerations are particularly supported by relevant structure context elements of the CBAM method.

3.5. Integrate Flexible and Dynamic Lighting Design

As revealed through the physical context element of the time, children are active at night. The reason may be that the time after school and after dinner gives them a certain degree of freedom to play with their neighbor friends in their own community. However, lighting conditions at night are relatively lacking, even though lighting is a critical physical context element in the activities of running and chasing. Note the interrelation between this physical context element and some psychological context elements such as safety in the CBAM descriptions of running and chasing. On the other hand, it should be noted that some psychological context elements like excitement may also be related in a way that a little darkness of lighting context element may rather enrich their values.

Given the frequency of nighttime activities and the limitations of ambient lighting, it is recommended to incorporate dynamic lighting systems that provide adaptable illumination without compromising the immersive atmosphere of play. These systems may include motion-sensor lights, low-level pathway lighting and interactive glowing installations, which serve the dual purpose of enhancing safety and deepening the immersive experience.

Lighting should not be overly harsh; according to research in environmental psychology [28,29], both the color temperature and illuminance of light sources should be carefully considered. Warm-toned lighting in combination with colorful point lights can create a visually engaging environment while maintaining comfort and orientation for children during evening play.

3.6. Integrate Spatial Layers for Dynamic and Static Activities

Children’s play often involves a combination of dynamic activities, such as running and throwing and static activities such as hiding and seeking. According to the CBAM analysis, different pathway structures are required to support activities like running versus hiding. Careful planning of movement routes within the spatial layout is essential to accommodate these varying needs.

Therefore, it is recommended to delineate zones for dynamic activities and zones for static engagement within the space. Design elements such as raised platforms, enclosed structures and vertical layering can be used to provide appropriate spatial support for different types of activities, enhancing both play diversity and functional clarity.

4. Discussions

In this section, discussions on the roles of CBAM as a structured framework of play space design and research contributions are provided based on the demonstrated design suggestions in the previous section derived from the detailed CBAM descriptions of child play activities of Section 2.

Firstly, those six design strategies of Section 3 as derived from activities are illustrated in Figure 10 showing from what specific space structure elements represented in specific CBAM of the activities these were derived. Strategy 3.1 about ground surface, for example, was derived from the relevant structures of activities of Run, Chase, Hide and Seek as corresponding mappings are shown in green lines in the figure. Strategies 3.2, 3.3, 3.4, and 3.6 are also mapped through corresponding relevant structures of the activities. Note that strategy 3.6 is mapped through relevant structures of two activities of Run and Chase explicitly, and implicitly through those two activities of Hide and Seek as shown in dotted connecting lines in the figure. On the other hand, strategy 3.5 about lighting design is mapped through physical context element on lighting from activities Run and Chase as shown in blue lines in the figure.

4.1. Focusing on Activity-Centered Design Framework

CBAM provides a systematic methodology for analyzing the interplay between children’s activities and spatial elements. By decomposing activities into their elements like actors, objects, tools, as well as goal contexts, relevant structure contexts, physical contexts and psychological contexts, the model makes visible the often-overlooked relationships between behavior and environment. In comparison with the Activity/Space ontology [16], where performer, consumer, equipment, service, time and constraints are simply listed so that relationships between these should be further specified, the CBAM method describes the activity elements in their specifically designated fields where objects and tools are clearly distinguished and context elements are represented in their clear distinctive semantics with goals, relevant structures, physical and psychological contexts. Activity elements are specified in a comprehensive and specific manner in the CBAM method. Designers familiar with the CBAM framework would address necessary interaction properly. While those psychological contexts such as safety in the work in this paper were determined based on observations of designers and researchers, emotion and experience related psychological context elements can be evaluated subjectively by active actors as in the case of [26] so that design improvements can be pursued reflecting actor’s personalized experiences in the future work. This approach contrasts with traditional design practices that prioritize aesthetics and functionality over experiential and behavioral needs.

4.2. CBAM as a Method to Improve Play Space Design

CBAM serves as a valuable method for enhancing space design by offering a deeper understanding of how spatial and structural elements influence children’s activities. Through its focus on context-based activity modeling, CBAM enables designers to anticipate the needs of young users and integrate these insights into more effective and behaviorally supportive environments. Specifically, as illustrated in Figure 10, the relevant structure context elements of CBAM offer very structured role in supporting designing of diverse necessary spatial and physical structures. Note that spatial strategies of Section 3 are described verbally rather than visually as they are very generic strategies, which can be applied to various contexts where spatial dispositions can be varied a lot.

4.3. CBAM Enables Accommodating Experience Aspects of Child Actors in Play Space Design

CBAM enables encompassing children actor experiences through its psychological context elements. Using psychological context elements and other activity elements such as relevant structure context elements, dynamic relationships between environment elements and activities can be addressed. In this way, CBAM helps ensure that the design of children’s play spaces is not only functional but also responsive to the evolving experiential and social needs of children. Note that various approaches can be utilized in representing psychological contexts, for example, from observations and surveys obtained through the user research stage to real-time subjective and dynamic experience evaluations of actors [26].

5. Conclusions

This study, based on the CBAM method, interrogated children’s play activities such as throw, run, chase, hide, seek, and seize as observed from the sandbag game in a community courtyard setting. Through the identification of activity context elements, it is found that children’s play activities are highly dependent on physical structures of the relevant structure context, including covering structures, ground surface materials, pathway layout, and spatial boundaries as well as child clothes. These structures serve not only as mediating elements that trigger activity but also play a crucial role in enhancing safety and emotional experiences and fostering a sense of engagement. Based on the CBAM approach, six specific design strategies are proposed in this paper for enhancing the design of outdoor children’s play environments.

In space design, knowledge of activity and required functionality is to be transformed into realized structure and spatial knowledge. Many of space design models focus on the structure and the function of space design [16], but not on activities for which the space is provided. In this paper, CBAM is proposed as a framework for activity-centered space design for child playground. Experiential sustainability of children’s play activities are supported by play space design fully addressing detailed context elements of CBAM such as relevant structure and psychological contexts. Note that the CBAM method would be valuable when space design is not properly conducted for children play activities as in the case where children are playing in a more general community spaces as often happens in our current living environments rather than dedicated children’s playgrounds. As mentioned in the introduction section about previous work [5,6] on children play behavior, children conduct a lot of diverse activities, which are not originally intended and thus not well supported by designed environment structural elements. As demonstrated in the case of sandbag game of the paper, the CBAM method with comprehensive and structured representation of space structure elements critical to activities would serve the framework in designing playground and improving other community spaces where children spend significant time in playing. It can be noted that the CBAM-based playground design method would be less powerful in a well-design play spaces as can be found in some apartment complex where play activities are narrowly specified.

The proposed methodology based on the CBAM method of the paper can be summarized as in the part shown in pink color in Figure 11. Children play activities in community spaces are observed. Key activities are represented in a structured and comprehensive manner by the CBAM method. Then, space structural elements of CBAM such as objects, tools, and relevant structures as well as some physical contexts are interrogated in relation with observations on psychological elements. Findings from the interrogation can be proposed as space structure design strategies for playground.

As immediate future work, CBAM-based activity descriptions and play space design suggestions, as conducted in this research, can be applied to a few more play games. Also, space design strategies identified through CBAM-based interrogations can be implemented in pilot projects so that children experiences can be evaluated in service prototyping involving child actors. Context-specific experience sampling and analysis (CESA) method with real-time actor evaluations in subjective manner using digital tools [26] can be used for such evaluations. With iterations of service prototyping, improvements on play space design in such community spaces can be enabled. This future work is shown in blue color in Figure 11.

Then, a repository of play activities and play space design suggestions can be constructed in future work as shown in green color in Figure 11. For space design of a new play game, similar aspects of play activities in the repository could be used so that play space design suggestions can be retrieved and transformed reflecting corresponding context differences between repository activities and new game activities. Toward this, a product-service systems [30] design approach, where human activities and product and space elements are systematically designed in an integrated manner, should be taken and integrated digital representation and interrogation systems would need to be developed as in the case of manufacturing servitization field [31].