Some Web-Based Experiences from Flipped Classroom Techniques in AEC Modules during the COVID-19 Lockdown

The classroom closure during the first semester of 2020 entailed decisive changes in higher education Universities have become more digital in both the availability of e-resources and pervasive devices and how students communicate with lecturers and classmates Learners adapted their study habits with a growing role of self-paced, internet-based strategies Some flipped learning approaches have proven their efficacy under the remote-teaching physical constraints This study aimed to appraise the outcomes from the implementation of various web-based, learning-aid tools on flipped teaching approaches in engineering modules The open educational resources (OER) performed satisfactorily during the lockdown period in three universities from two countries with similar higher education models Such resources encompassed classroom response systems and web-based exercise repositories, designed for diverse purposes such as autonomous learning, self-correction, flipped classroom, peer assessment, and guided study The acquired experiences reveal that OER helped students to enhance their engagement, reach the deeper levels of the cone of learning, and widen their range of learning abilities This procedure is easily attainable for architecture, engineering, and construction (AEC) courses and lifelong learning settings Feedback from students, instructors’ perceptions, and learning outcomes show the suitability and effectiveness of the web-based learning assistant procedure presented here


Introduction
During the first months of 2020, universities all around the world had to face a sudden shift to online learning, due to lockdown, as a consequence of the COVID-19 global pandemic. Since this situation overcame with no time for preparing, the teaching resources, nor the technological means that online teaching implies, it can be argued that, in general, universities were not prepared to face this challenge and a huge effort had to be made by institutions and lecturers in order to handle teaching in the most satisfactory way.
Moore and Kearsley [1] defined online teaching as a planned learning that takes place in a different location where it is taught and other authors [2][3][4] made a distinction between the online synchronous teaching (real-time interaction) and the online asynchronous teaching (no real-time interaction). It is clear, nowadays, that the World Wide Web (WWW) not only facilitates asynchronous learning, allowing anytime and anywhere learning, but it also makes synchronous teaching by means of virtual meetings using video-calls easier [5]. The WWW provides a wide range of teaching possibilities that have been exploited intensely during more than two decades [6,7], and nowadays, it is hard to imagine higher education without its use [8]. Nevertheless, these tools are usually combined with other tablished are not guaranteed to function from now. The pure lecture model may no longer be an acceptable teaching pedagogy, as the rise of technology has arrived to stay [30].
The impact of the pandemic on higher education is still open for debate, and guidelines, experiences, and recommendations are increasingly emerging [31,32]. Web-based learning frameworks have gained presence during the development of digital transformation of universities [28,33]. As students are digital natives, it appears necessary to identify their perspective on the use of technology in the academic context, as well as with what purpose and operations students use the technologies, and to understand what their expectations are [26,34]. At the same time, it seems attainable to harness the benefits of digital media to communicate with them and guide their training. One interesting technique is the inquiry-based learning by using the so-called Immediate Response Systems (IRS)-or Student Response Systems (SRS) or Classroom Response Systems (CRS) [35][36][37]. These include elements such as the development of a positive relation with failure, objectivity, and continuous assessment as usual targets. They also introduce breakpoints during impartations to recall student attention and focus on key aspects of the lessons [38,39].
Diverse studies focused on evaluating the readiness of lecturers and the feasibility of LMS [40,41], others on collecting students' perceptions [42][43][44], on analyzing the impact of the online format on studying at home [44,45], on learning achievements [46,47], and on the efficiency of flipped teaching methods [44,[48][49][50][51][52]. It appears that blended learning methods have suffered less than other teaching approaches during this sudden shift to remote teaching [51]. However, lecturers had to harness the best of flipped teaching and adapt it to a completely virtual context [44,[49][50][51][52]. Other studies addressed the social impact of the pandemic crisis on the professional careers [53] and the lecturer's role [54], as well as the relationship between lecturers and learners [55]. Nevertheless, these are currently open fields for debate [56].
This study aims to appraise the outcomes from implementing various web-based learning-aid tools on flipped teaching approaches in engineering modules: the use of CRS, web-based repositories of problems and exercises, pre-recorded videos, and a problembased learning approach for technological Master's engineering courses.
This study collects both lecturers' and students' perceptions and feedback with the aim of implementing further teaching measures. The information gathered comprises lecturers' perceptions, final grades, learning outcomes, feedback from online questionnaires delivered to students, as well as individual and group interviews.

Methodology
This study belongs to a collaborative project carried out by professors of the Universidad Politécnica de Madrid (UPM, Madrid, Spain), Universidad de Jaén (UJA, Linares, Spain) and Universidad de Piura (UDEP, Piura, Perú). The scope was to share techniques, methods, resources, and strategies for home and classroom learning in accordance with the United Nations Educational, Scientific and Cultural Organization (UNESCO) recommendation in promoting and reinforcing international cooperation in open educational resources (OER) [33]. The project focuses on applying innovative methods in higher education since digital technology and remote instruction are stepping ahead of face-to-face teaching [57]. The methodology aims at helping students to improve their learning of some key concepts of structural analysis, construction management, and operations research, although it is easily implementable in courses of other AEC disciplines.
This work builds on a renewed boost of a merged learning technique under the convergence between distance and face-to-face learning for undergraduate students of fundamental subjects in civil engineering [58]. It focuses on the use of digital resources for integrating their autonomous homework with classroom involvement and aims to swap passive class time for just-in-time teaching, give quality time classes, improve achievements, and enhance the instructor's role [28]. Thus, the application of OER contributes to increasing the number of e-resources available to the community following the current digital transformation trend undertaken by universities [33,59]. Some essential features of the OER described are scalability, third-party availability, and transferability. In this regard, other AEC teaching units holding these modules can either use or adapt these contents as needed. Such a repository can also be reshaped as an e-resource for lifelong learning experiences, through which alumni can refresh or update some technical concepts over the years [60].
Learning Management Systems (LMS) have been increasingly used in higher education, albeit played a noticeable role during the lockdown period. Furthermore, some tools such as CRS-also called Immediate Response Systems (IRS)-, repositories of web-based interactive problems and videos have proven effective for calling student engagement and prompting them for active learning [37].
On the one hand, formative assessment is admitted to enhancing learners' achievement based on seeking success through failure [61][62][63]. Nevertheless, this methodology must address three well spotted challenges: (1) how to be effective in promoting meaningful learning, (2) how to tailor grading practices that promote personal improvement rather than competition, and (3) assessment feedback may cause a negative impact on low-achieving students, who are prone to seem to be unable to learn and may become discouraged [59,60]. In this regard, the CRS approach allows an instructor to collect feedback immediately and relies on the individual discretion, as most students are reluctant to speak up and engage in large groups. CRS may become a useful ingredient of the question-driven instruction (QDI) approach, occasionally used together with traditional teaching practice, instead of the classical transmit-and-test classroom model [64,65].
The methodology applied in this project aims at leveraging students' digital skills, boosting their active participation in remote teaching and assessing their learning. The target is to improve learning outcomes for both undergraduate and graduate engineering students. This study explores some results from the application of various student response systems in the classroom (SRS, IRS or CRS), namely Kahoot!, Socrative and Mentimeter.
On the other hand, the web-based tools aim to boost students' receptive and productive skills while learning the principles and the elusive concepts of construction-related subjects. A large percentage of students encounter difficulties in acquiring the knowledge of the basic principles of behavior of some usual structural typologies related to civil engineering constructions.
The OER described here were intended to enhance students' capabilities and spatial reasoning skills for envisaging the physical meaning of some intricate underlying concepts. The learning aid approach presented here encompasses a repository of interactive exercises and problems, written in HTML5, CSS and JavaScript, and is based on a problem-solving strategy. This tool is also adequate for self-correction, self-assessment, flipped teaching, guided study, and peer assessment, among other features [66,67]. This e-learning tool boasted good performance and acceptance during the confinement period at both UPM and UJA.
The indicators considered include the students' perception of the usefulness and benefits of the system employed, the agreement between expectation and system performance, satisfaction upon using the web-based systems, and the users' readiness to continue using the system in future courses.
This study also handled diverse control variables such as the teaching modality (synchronous or asynchronous), the course type (fundamental or technological, undergraduate or graduate), the instructor's predisposition and readiness to innovate, and previous experience with educational innovation, among others.
The students were surveyed twice during the semester and invited to participate in either individual or group interviews. Survey results provided quantitative data about student usage of digital technology, their purposes, the ways they did, and for what tasks. The interviews and observed classes provided valuable information around their reasons to do so.

Classroom Response Systems (CRS, SRS or IRS)
The changes in higher education have involved significant changes in the learningteaching system, starting from the lecturer and reaching the students. Universities have encouraged the teaching staff to introduce modifications in the traditional teaching techniques. One of the main issues in AEC and science, technology, engineering, and mathematics (STEM) disciplines is the use of new methodologies and technology in the evaluation tasks, seeking to enhance the motivation of the students. This is a key aspect because there is a direct relation between the motivation of the students and their results. Since the 2017-2018 academic year, the assessment of Construction Management combined both the traditional methodology with some gamification approach based on Kahoot, Socrative, and others. These apps allow performing questionnaires in the classroom in real time. Moreover, the answers of the students can also be evaluated in real time, and after each question, a ranking of the students is shown. This permits the lecturer to focus on the main points of the lesson as well as breaking the monotony of the lecture at any time the lecture considers. In order to promote the daily study of the modules, a certain percentage of the final mark was obtained through the analysis of the Kahoot! tests. The influence of introducing such techniques, in the motivation towards the modules, was assessed by a test whose results can be seen in Figure 1. student usage of digital technology, their purposes, the ways they did, and for what tasks. The interviews and observed classes provided valuable information around their reasons to do so.

Classroom Response Systems (CRS, SRS or IRS)
The changes in higher education have involved significant changes in the learningteaching system, starting from the lecturer and reaching the students. Universities have encouraged the teaching staff to introduce modifications in the traditional teaching techniques. One of the main issues in AEC and science, technology, engineering, and mathematics (STEM) disciplines is the use of new methodologies and technology in the evaluation tasks, seeking to enhance the motivation of the students. This is a key aspect because there is a direct relation between the motivation of the students and their results. Since the 2017-2018 academic year, the assessment of Construction Management combined both the traditional methodology with some gamification approach based on Kahoot, Socrative, and others. These apps allow performing questionnaires in the classroom in real time. Moreover, the answers of the students can also be evaluated in real time, and after each question, a ranking of the students is shown. This permits the lecturer to focus on the main points of the lesson as well as breaking the monotony of the lecture at any time the lecture considers. In order to promote the daily study of the modules, a certain percentage of the final mark was obtained through the analysis of the Kahoot! tests. The influence of introducing such techniques, in the motivation towards the modules, was assessed by a test whose results can be seen in Figure 1. Therefore, some gamification methods were used before the COVID-19 lockdown and these previous experiences served as an approach to what was needed after the pandemic situation. At the time of writing, many implementations have been included in the modules Construction Management in the Bachelor's degree in Civil Engineering and Smart Construction: BIM in the Master's degree in Civil Engineering. However, the perception is that Kahoot! was already known and several new options, such as Socrative and Mentimeter, helped to improve the motivation during the lockdown. Mentimeter works in a similar way, although it features several new options such as the one shown in Figure  2 that help lecturers to promote student participation. Therefore, some gamification methods were used before the COVID-19 lockdown and these previous experiences served as an approach to what was needed after the pandemic situation. At the time of writing, many implementations have been included in the modules Construction Management in the Bachelor's degree in Civil Engineering and Smart Construction: BIM in the Master's degree in Civil Engineering. However, the perception is that Kahoot! was already known and several new options, such as Socrative and Mentimeter, helped to improve the motivation during the lockdown. Mentimeter works in a similar way, although it features several new options such as the one shown in Figure 2 that help lecturers to promote student participation. Educ Some other tools were implemented during the lockdown given that there was not any possibility of student visits to construction sites. This activity was performed twice during the semester every academic year. Thus, this activity was substituted by the use of videos related to the construction processes and the management. In the same sense, Computer Laboratory activities in which the students learn how to use construction related software were also substituted by video-lectures. The main problem that the teaching staff had to face was that it was difficult to follow the assessment and the student could not see all the videos prepared for that aim. In such a sense, the use of Edpuzzle was of special interest as it permits inserting questions in the video sequentially. Thus, the students had to answer all the questions and the lecturer could see if they had seen it completely. After that, some exercises to put in practice, and the content of the video, were also proposed and marked for each of the activities.

Problem-Based Learning (PBL) and Classroom Response Systems (CRS) Strategies
PBL and CRS strategies were also designed with the aim of getting students to participate in knowledge reworking activities, as well as allowing them to get involved in real situations. Engineers use mathematics to describe and interpret situations, but find it difficult to identify, in the context of their work, the mathematics they have learned and envisage their physical implications.
The modules included in this study focus on practical and professional issues that students need to attain. This justifies that most classes are technologically oriented so students should achieve a variety of competences by means of a sequence of problems, projects, and challenges with increasing complexity. In this regard, the web tools presented can be properly applied in problem-based teaching practices [8]. Pre-recorded videos and the repositories of both online quizzes and interactive problems on Strength of materials, Structural analysis, Construction management and Operations research are intended to be used with the problem-based model.

Web-Based Strategies
This line of action aims to boost students' receptive and productive skills while learning the fundamentals of Structural Analysis. It draws on the difficulties encountered by a large percentage of the students in understanding the implications of the principles that govern the response of some simple structures with widespread application in civil engineering constructions. Some other tools were implemented during the lockdown given that there was not any possibility of student visits to construction sites. This activity was performed twice during the semester every academic year. Thus, this activity was substituted by the use of videos related to the construction processes and the management. In the same sense, Computer Laboratory activities in which the students learn how to use construction related software were also substituted by video-lectures. The main problem that the teaching staff had to face was that it was difficult to follow the assessment and the student could not see all the videos prepared for that aim. In such a sense, the use of Edpuzzle was of special interest as it permits inserting questions in the video sequentially. Thus, the students had to answer all the questions and the lecturer could see if they had seen it completely. After that, some exercises to put in practice, and the content of the video, were also proposed and marked for each of the activities.

Problem-Based Learning (PBL) and Classroom Response Systems (CRS) Strategies
PBL and CRS strategies were also designed with the aim of getting students to participate in knowledge reworking activities, as well as allowing them to get involved in real situations. Engineers use mathematics to describe and interpret situations, but find it difficult to identify, in the context of their work, the mathematics they have learned and envisage their physical implications.
The modules included in this study focus on practical and professional issues that students need to attain. This justifies that most classes are technologically oriented so students should achieve a variety of competences by means of a sequence of problems, projects, and challenges with increasing complexity. In this regard, the web tools presented can be properly applied in problem-based teaching practices [8]. Pre-recorded videos and the repositories of both online quizzes and interactive problems on Strength of materials, Structural analysis, Construction management and Operations research are intended to be used with the problem-based model.

Web-Based Strategies
This line of action aims to boost students' receptive and productive skills while learning the fundamentals of Structural Analysis. It draws on the difficulties encountered by a large percentage of the students in understanding the implications of the principles that govern the response of some simple structures with widespread application in civil engineering constructions.
The formal object encompasses the combination of web-based tools with other open educational resources (OER), which altogether contribute to enlarging the availability of the so-called e-textbooks [14], necessary for the blended learning models implemented at these teaching units. The web-based material focuses on enhancing students' spatial reasoning skills for envisaging the actual response of simple structures. This entails mastering concepts such as equilibrium, bending stiffness, force transmission, support conditions, moving loads, worst load combinations, and envelopes of response features. As a result, learners become able to identify the critical sections of a given structure and envisage the most unfavorable loading for a given structure.
The resource is freely available through any web browser. It encompasses a collection of pre-recorded videos with classes given by lecturers, a collection of pre-set Socrative tests and a repository of interactive problems and exercises written in HTML and JavaScript to be accessed through any web browser.
The pre-recorded videos harness the availability of the digital tablets as a modern version of the classical blackboard [68,69]. It is useful for both on-campus and remote teaching [70]. Figure 3 shows a snapshot of a screen during a class. Teaching with a tablet allows the lecturer to add colors and images easily, save the successive screens and voice, export them to digital format, and generate new e-resources. Tablets facilitate instructors the benefits of an attractive electronic lecture presentation and the ability to signal and jot down directly on the screen, remark relevant aspects, or respond to student queries. These are enormous advantages compared with the classical blackboard sessions. Besides, the tablet has proven to be a useful and effective device during the lockdown period for both tutorials and student follow-up. It has changed the classroom interaction and communication between students as well as collaborative work [71]. At the same time, it has become highly adequate for ubiquitous teaching [13]. Educ The formal object encompasses the combination of web-based tools with other open educational resources (OER), which altogether contribute to enlarging the availability of the so-called e-textbooks [14], necessary for the blended learning models implemented at these teaching units. The web-based material focuses on enhancing students' spatial reasoning skills for envisaging the actual response of simple structures. This entails mastering concepts such as equilibrium, bending stiffness, force transmission, support conditions, moving loads, worst load combinations, and envelopes of response features. As a result, learners become able to identify the critical sections of a given structure and envisage the most unfavorable loading for a given structure.
The resource is freely available through any web browser. It encompasses a collection of pre-recorded videos with classes given by lecturers, a collection of pre-set Socrative tests and a repository of interactive problems and exercises written in HTML and JavaScript to be accessed through any web browser.
The pre-recorded videos harness the availability of the digital tablets as a modern version of the classical blackboard [68,69]. It is useful for both on-campus and remote teaching [70]. Figure 3 shows a snapshot of a screen during a class. Teaching with a tablet allows the lecturer to add colors and images easily, save the successive screens and voice, export them to digital format, and generate new e-resources. Tablets facilitate instructors the benefits of an attractive electronic lecture presentation and the ability to signal and jot down directly on the screen, remark relevant aspects, or respond to student queries. These are enormous advantages compared with the classical blackboard sessions. Besides, the tablet has proven to be a useful and effective device during the lockdown period for both tutorials and student follow-up. It has changed the classroom interaction and communication between students as well as collaborative work [71]. At the same time, it has become highly adequate for ubiquitous teaching [13]. The collection of web-based problems and exercises has increased the OER available to learners and has been conceived for a multitasking purpose: autonomous learning, selfcorrection, flipped teaching, peer assessment and guided study. Its topic sequence follows the course syllabus development. Once the user has accessed, chosen the preferred language (Spanish or English) and topic, and selected an interactive exercise, they begin an interactive exercise. Then, a sequence starts, consisting of the statement, solving triggering, solution, rubric, and feedback provided by the system. The user can set the desired data values for physical and mechanical properties of the structural system, i.e., the span The collection of web-based problems and exercises has increased the OER available to learners and has been conceived for a multitasking purpose: autonomous learning, self-correction, flipped teaching, peer assessment and guided study. Its topic sequence follows the course syllabus development. Once the user has accessed, chosen the preferred language (Spanish or English) and topic, and selected an interactive exercise, they begin an interactive exercise. Then, a sequence starts, consisting of the statement, solving triggering, solution, rubric, and feedback provided by the system. The user can set the desired data values for physical and mechanical properties of the structural system, i.e., the span lengths, support conditions, load types and values, and flexural stiffness. Then the structural system is plotted on the screen.
After setting the problem data, upon clicking a "calculate" button, the system returns the numerical results and graphic output for the user-defined data. The latter draws on the advanced features of JavaScript and jQuery.
The user can browse back and forth throughout the diverse parts of the exercise, which includes a help context providing hints, remarks and comments at each solving step. Besides, these web pages may include some links to complementary short videos. In this way, the users can take ownership of his/her learning. To date, students have found them useful to understand the spatial impact of loading and support conditions on the structural response. In this regard, outcomes indicate that this collection of interactive problems and exercises is a helpful tool for autonomous learning.
Scalability is one advantage of this repository with interactive exercises and problems, either with increasing complexity or with the number of examples included of which a sample is shown in Figures 4 and 5 lengths, support conditions, load types and values, and flexural stiffness. Then the structural system is plotted on the screen. After setting the problem data, upon clicking a "calculate" button, the system returns the numerical results and graphic output for the user-defined data. The latter draws on the advanced features of JavaScript and jQuery.
The user can browse back and forth throughout the diverse parts of the exercise, which includes a help context providing hints, remarks and comments at each solving step. Besides, these web pages may include some links to complementary short videos. In this way, the users can take ownership of his/her learning. To date, students have found them useful to understand the spatial impact of loading and support conditions on the structural response. In this regard, outcomes indicate that this collection of interactive problems and exercises is a helpful tool for autonomous learning.
Scalability is one advantage of this repository with interactive exercises and problems, either with increasing complexity or with the number of examples included of which a sample is shown in Figures 4 and 5.   lengths, support conditions, load types and values, and flexural stiffness. Then the structural system is plotted on the screen. After setting the problem data, upon clicking a "calculate" button, the system returns the numerical results and graphic output for the user-defined data. The latter draws on the advanced features of JavaScript and jQuery.
The user can browse back and forth throughout the diverse parts of the exercise, which includes a help context providing hints, remarks and comments at each solving step. Besides, these web pages may include some links to complementary short videos. In this way, the users can take ownership of his/her learning. To date, students have found them useful to understand the spatial impact of loading and support conditions on the structural response. In this regard, outcomes indicate that this collection of interactive problems and exercises is a helpful tool for autonomous learning.
Scalability is one advantage of this repository with interactive exercises and problems, either with increasing complexity or with the number of examples included of which a sample is shown in Figures 4 and 5.

Teaching-Learning Experiences during COVID-19 Lockdown
A summary of the experiences carried out during the lockdown period in engineering modules of the above mentioned three universities is described in this section. Such experiences deal with flipped classroom techniques under the physical constraints of remote teaching and evaluation. The experiences described here correspond to courses including Strength of materials, Smart construction: BIM, Construction management, Elasticity and Strength of materials II, Operations research I and II, and Dynamic and seismic analysis of structures. These semester modules were taught remotely and engaged 671 registered students.
Some sets of pre-recorded videos with teachings played a core role among the eresources used in the accomplished flipped-teaching model. Indeed, they constituted a remarkable resource for the autonomous learning stage. Each subject has its own growing collection, which is reviewed on a semester basis. Lecturers prompt students to visualize some videos and do some homework, mainly exercises and problems. To ensure their viewing and comprehension of these multimedia files available for individual study, the pre-recorded videos included short questions sparsely inserted (Edpuzzle) so that students could only continue watching them after replying. Learners highly valued this feature as a motivating feature.
The first class time after the homework study stage was devoted to both testing the at-home individual learning and just-in-time teaching. The former included performing online quizzes through the CRS or responding to an on-the-fly exercise, which resembled the assigned homework, as a way to encourage students in their active learning. The latter helps to promote the use of class time for intensifying active learning [64,72,73]. The underlying purpose of this blended learning approach comprised four ingredients:

•
Encouraging open discussion, giving more dynamic classes and lessons more interactively.

•
Using technology properly to enhance engagement. • Keeping, when possible, concise sessions within class time, diversifying activities to avoid boring one or two-hour passive sessions.

•
Integrating some type of entertainment and professional perspectives in training.

Classroom Response Systems
In order to assess their individual learning in the fundamental degree subjects, students were prompted to solve at-home weekly exercises delivered through the LMS and to make short online quizzes with the IRS at least once a week during class time. The digital tools employed were Kahoot, Socrative, and Mentimeter. Figure 6 shows a snapshot of a Socrative item.

Teaching-Learning Experiences during COVID-19 Lockdown
A summary of the experiences carried out during the lockdown period in engineering modules of the above mentioned three universities is described in this section. Such experiences deal with flipped classroom techniques under the physical constraints of remote teaching and evaluation. The experiences described here correspond to courses including Strength of materials, Smart construction: BIM, Construction management, Elasticity and Strength of materials II, Operations research I and II, and Dynamic and seismic analysis of structures. These semester modules were taught remotely and engaged 671 registered students.
Some sets of pre-recorded videos with teachings played a core role among the e-resources used in the accomplished flipped-teaching model. Indeed, they constituted a remarkable resource for the autonomous learning stage. Each subject has its own growing collection, which is reviewed on a semester basis. Lecturers prompt students to visualize some videos and do some homework, mainly exercises and problems. To ensure their viewing and comprehension of these multimedia files available for individual study, the pre-recorded videos included short questions sparsely inserted (Edpuzzle) so that students could only continue watching them after replying. Learners highly valued this feature as a motivating feature.
The first class time after the homework study stage was devoted to both testing the at-home individual learning and just-in-time teaching. The former included performing online quizzes through the CRS or responding to an on-the-fly exercise, which resembled the assigned homework, as a way to encourage students in their active learning. The latter helps to promote the use of class time for intensifying active learning [64,72,73]. The underlying purpose of this blended learning approach comprised four ingredients:


Encouraging open discussion, giving more dynamic classes and lessons more interactively.  Using technology properly to enhance engagement.  Keeping, when possible, concise sessions within class time, diversifying activities to avoid boring one or two-hour passive sessions.  Integrating some type of entertainment and professional perspectives in training.

Classroom Response Systems
In order to assess their individual learning in the fundamental degree subjects, students were prompted to solve at-home weekly exercises delivered through the LMS and to make short online quizzes with the IRS at least once a week during class time. The digital tools employed were Kahoot, Socrative, and Mentimeter. Figure 6 shows a snapshot of a Socrative item. During class time and after closing the online quiz, the lecturer solves the problem or exercise on the tablet and responds to queries or difficulties raised by the students. During class time and after closing the online quiz, the lecturer solves the problem or exercise on the tablet and responds to queries or difficulties raised by the students.
Survey results indicate that students highly appreciate the use of IRS in their learning process, as this helps them to make the pedagogical practice more dynamic and point out the relevant issues of a subject.

Web-Based Parameterized Problems (UJA and UPM)
The use of flipped-learning techniques is starting to be introduced in several courses of Civil and Mechanical Engineering at University of Jaén (UJA). In these courses, mainly dealing with Strength of Materials, it is of paramount importance to help students to master the most relevant aspects regarding the way the beams behave under different loading scenarios, how they modify their bending moment and shear stresses diagrams, as well as their deformation. These abilities are fundamental for the students to understand more complex structures that are covered in later courses of these degrees.
In this case, the use of web-based problems is focused on flipped-learning experiences where the teacher guides students through a specific problem to make them think and question their knowledge about key aspects regarding the behavior of a beam under loading. The main goal is to stimulate students and deepen their knowledge, so they acquire a certain intuitive understanding of how structures work.
The experience is carried out as follows: at the end of a class, the students are presented a new problem to solve, which has several parameters that can adopt different values (Figure 3 shows one of the proposed problems). This problem can be solved by means of a web page where students can experiment by modifying the values and observing the results in an interactive way (they see the resulting bending moment and shear stresses diagrams, the deflection of point D). The main goal of this problem is not to solve it, which can be easily done with the web page, but thinking of several key issues that the students must try to guess by intuition and, then, check with the help of the web-based problem. To this end, the students are given a set of questions to answer regarding the proposed problem. In the case of the problem shown in Figure 7, for example, they were questioned about how load P affects deflection of point D (does increasing P make D move upward or downward?) and whether load q induces a positive or negative moment in A. Before the next class, the students must use the web page to solve these questions and check if their intuition is correct about them. Finally, at the beginning of the next class, the teacher opens a debate where students talk about their findings. This debate takes no longer than fifteen minutes, but it is extremely rich, since it helps students to connect their knowledge and better understand how structures work. They must be able to solve problems by using specific methods taught in class. They also have the chance to understand them better, often connecting some concepts with others, finding out that what they have learned in different courses are not isolated boxes, but related. The lecturer conducts this debate to help them to find the correct conclusions.

Web-Based Parameterized Problems (UJA and UPM)
The use of flipped-learning techniques is starting to be introduced in several courses of Civil and Mechanical Engineering at University of Jaén (UJA). In these courses, mainly dealing with Strength of Materials, it is of paramount importance to help students to master the most relevant aspects regarding the way the beams behave under different loading scenarios, how they modify their bending moment and shear stresses diagrams, as well as their deformation. These abilities are fundamental for the students to understand more complex structures that are covered in later courses of these degrees.
In this case, the use of web-based problems is focused on flipped-learning experiences where the teacher guides students through a specific problem to make them think and question their knowledge about key aspects regarding the behavior of a beam under loading. The main goal is to stimulate students and deepen their knowledge, so they acquire a certain intuitive understanding of how structures work.
The experience is carried out as follows: at the end of a class, the students are presented a new problem to solve, which has several parameters that can adopt different values (Figure 3 shows one of the proposed problems). This problem can be solved by means of a web page where students can experiment by modifying the values and observing the results in an interactive way (they see the resulting bending moment and shear stresses diagrams, the deflection of point D). The main goal of this problem is not to solve it, which can be easily done with the web page, but thinking of several key issues that the students must try to guess by intuition and, then, check with the help of the web-based problem. To this end, the students are given a set of questions to answer regarding the proposed problem. In the case of the problem shown in Figure 7, for example, they were questioned about how load P affects deflection of point D (does increasing P make D move upward or downward?) and whether load q induces a positive or negative moment in A. Before the next class, the students must use the web page to solve these questions and check if their intuition is correct about them. Finally, at the beginning of the next class, the teacher opens a debate where students talk about their findings. This debate takes no longer than fifteen minutes, but it is extremely rich, since it helps students to connect their knowledge and better understand how structures work. They must be able to solve problems by using specific methods taught in class. They also have the chance to understand them better, often connecting some concepts with others, finding out that what they have learned in different courses are not isolated boxes, but related. The lecturer conducts this debate to help them to find the correct conclusions. During these experiences, only about 25% of the students proved to work properly on the problem, the rest only used the web-based problem occasionally but did not think much about the proposed questions. This can be because this was a new experience to them, and they were not used to it. Nevertheless, the experience was interesting for all the During these experiences, only about 25% of the students proved to work properly on the problem, the rest only used the web-based problem occasionally but did not think much about the proposed questions. This can be because this was a new experience to them, and they were not used to it. Nevertheless, the experience was interesting for all the students, since all of them were present in the debate, which helped them find the same conclusions as the rest.
The web repository of parameterized exercises and problems also proved to be an adequate resource for guided-study class sessions. The lecturer hands out an online exercise and explains the basic guidelines to solve it. No two data sets are alike, since the statement data (spatial layouts, stiffness, loads, etc.) are functions of the registration number of learners. They attempt to solve each one's exercise and hand it in to the LMS. Then, the lecturer unlocks the URL with the interactive problem so that students can check their corresponding numerical results and find complementary hints. Besides, they can raise queries and arguments, thus converting this part of the class in quality time.

Web-Based Parameterized Problems (UDEP)
The undergraduate third-year students to whom UDEP allocated the experience featured organizational skills, teamwork ability and responsibility still in the making. Besides, given their work context (social isolation, very large classes, and extensive syllabi), the teachers conducted the research, raised the problems and targets, provided the bibliography and resources, and performed activities to ensure that the students developed the necessary work and achieved the expected knowledge.
The PBL-CRS strategies used in the Operations Research dictation experience encompassed the autonomous study of the theoretical framework and the ex-post resolution of problems assigned to the students, either individually or in teams. The achievement indicators included the application of an algorithm, the ability to introduce a new concept or procedure, to deepen its meaning or usefulness, and/or problem aspects that raised learning difficulties.
With this PBL-CRS strategy, students must argue their answers, thus avoiding random or improvised responses. Unlike the traditional teaching practice consisting of asking questions throughout the session, which involves only a few motivated students, the employed strategy includes a structured questioning process, what requires the participation of the entire class. The autonomous homework stage comprises studying the theoretical background, doing exercises, responding to short quizzes, and designing brief projects. In this regard, they have available the support material and e-resources on the LMS (UDEP Virtual), which constitutes a program of activities that can be carried out either individually or in teams. Thus, they can demonstrate competence achievement for each stage by advancing in the resolution of problematic situations. Figure 8 shows the students' satisfaction survey on the comparison between remotely oriented work and traditional teaching on Operations Research at UDEP.
adequate resource for guided-study class sessions. The lecturer hands out an online exer-cise and explains the basic guidelines to solve it. No two data sets are alike, since the statement data (spatial layouts, stiffness, loads, etc.) are functions of the registration number of learners. They attempt to solve each one's exercise and hand it in to the LMS. Then, the lecturer unlocks the URL with the interactive problem so that students can check their corresponding numerical results and find complementary hints. Besides, they can raise queries and arguments, thus converting this part of the class in quality time.

Web-Based Parameterized Problems (UDEP)
The undergraduate third-year students to whom UDEP allocated the experience featured organizational skills, teamwork ability and responsibility still in the making. Besides, given their work context (social isolation, very large classes, and extensive syllabi), the teachers conducted the research, raised the problems and targets, provided the bibliography and resources, and performed activities to ensure that the students developed the necessary work and achieved the expected knowledge.
The PBL-CRS strategies used in the Operations Research dictation experience encompassed the autonomous study of the theoretical framework and the ex-post resolution of problems assigned to the students, either individually or in teams. The achievement indicators included the application of an algorithm, the ability to introduce a new concept or procedure, to deepen its meaning or usefulness, and/or problem aspects that raised learning difficulties.
With this PBL-CRS strategy, students must argue their answers, thus avoiding random or improvised responses. Unlike the traditional teaching practice consisting of asking questions throughout the session, which involves only a few motivated students, the employed strategy includes a structured questioning process, what requires the participation of the entire class. The autonomous homework stage comprises studying the theoretical background, doing exercises, responding to short quizzes, and designing brief projects. In this regard, they have available the support material and e-resources on the LMS (UDEP Virtual), which constitutes a program of activities that can be carried out either individually or in teams. Thus, they can demonstrate competence achievement for each stage by advancing in the resolution of problematic situations. Figure 8 shows the students' satisfaction survey on the comparison between remotely oriented work and traditional teaching on Operations Research at UDEP.

Results and Discussion
The web-based resources used for flipped-learning techniques, where the teacher guides the students through some key aspects of the behavior of structures, proved to be of great interest, particularly during the lockdown period. A correctly designed and guided experience by the teacher provides students with a valuable opportunity to think about some general structural aspects that can be eluded by only solving problems using specific methods taught in class [19,25].
The students' participation was somewhat limited, but the final debates that led to highlight the main conclusions took place in front of all the students, so any could follow the most meaningful aspects of the problems.
In this experience, an alternative to traditional engineering teaching has been implemented, developing activities based on the PBL model and adopting a CRS to improve communication in the classroom. The design of the activities took into consideration some learning difficulties and the related teaching proposals and advice identified by the research on the field [34,[49][50][51][52]. In this regard, noticeable differences resulted in the suitability of web-based methods between undergraduate courses and Master's courses, and between fundamental and technological modules.
Some of the items included in the surveys were: (1) Degree of satisfaction with the individual learning experience.
(2) Usefulness of such implementation in class time.
(3) Applicability of this procedure to other units in this module.
(4) Fulfilment of learning expectations. (5) Initial individual readiness to perform the task. (6) Current readiness after having performed the task. (7) Readiness to perform the task in groups. Table 1 shows the results from 220 survey respondents for an undergraduate module taught during the confinement period. Students were also surveyed about the exams, the usefulness and adequacy of OER. Table 2 shows feedback for technological modules at UPM and UDEP for the following questions: (1) The ease of last exams: (5) very difficult; (1) very easy.
(2) Adequacy of exams to the subject syllabus.  • What lessons have been more beneficial in the use of the web-based resources? Around 65% of students witnessed that those interactive exercises associated with the first few chapters ranked at the top because they were helpful to grasp the principles and fundamentals of the module.

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Which are the most complex problems of the repository? Half of survey takers pointed at those of the second half of the course, associated with more advanced concepts. • Which improvement opportunities are the users demanding? Around 25% of students' suggestions or comments were fair enough to be considered for improving either the content or the structure of the repository. • Which other lessons or concepts are eligible for inclusion in the repository? Answers ranged from preliminary concepts and theoretical background to advanced topics that belong to subsequent modules.

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The ease and usability of the web-based tools: the mean value was 3.65 in a scale from one up to five.

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Other comments: 48% of surveyed students stated that they lacked the fundamentals needed to properly achieve the subject skills and learning.

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The dropout rate in fundamental subjects reached 22%, which was notably higher than in technological modules, which was lower than 10%.
Feedback from surveys, outcomes, and interviews indicate that the use of CRS promoted a mind shift in students: more than 50% have increased attendance and improved their achievements. More than 35% swapped shyness for active participation in the classroom, along with transferable skills. In exchange, they demand some reward for accomplishing these tasks. On the lecturer side, CRS become helpful instruments provided that they may make the classroom pedagogical practice more dynamic. Besides, CRS tasks yield a rapid assessment, which can become motivating for students and useful and low-effort demanding for teachers [74][75][76][77].
Two major forces have affected higher education during the lockdown period caused by the global sanitary crisis: digital technology for remote teaching and the policies and structures of higher educational entities. The former issues have increased the access, inclusion, and efficiency of some processes, albeit the outcomes seem to highly depend on its implementation [28] and monitoring [67]. Another remarkable benefit is that, when combined with some blended learning models, students can take ownership of their active learning [78][79][80]. Indeed, more than a few universities are boosting vice-rectorates of Strategy and Digital transformation. This passes through the modernization of equipment, facilities and digital media, but it must involve a widespread set of measures to tackle three pending tasks: the digital divide, inclusion, and the quality standards. The former entails that lecturers acquire digital competences accordingly [81]. The term inclusion refers to the ongoing, and transformative, process of improving education systems to meet all learners' needs, especially focusing on low-achieving students or students from low-income families.
Likewise, there is wide concern that universities are lowering the bar and dropping the standards, so student training is becoming poorer. Module requirements have lessened and the implicitly assumed levels of reading and writing are cutting off [82,83]. This entails that the students devote less and less time to their studies and fail to develop productive skills such as critical thinking, spatial reasoning, or argument abilities, among others [84]. As a result, some grade inflation seems to have appeared [85][86][87][88]. Many classes are still designed as passive lectures with few applications and scarce active engagement, which limits skill development and competence acquisition [89][90][91]. Conversely, achievement is directly linked to the stimulation of meaningful learning by delivering information in a clear and alluring way, relating it to the learners, and using conceptually demanding learning tasks [92]. This, indeed, involves the use of digital technology. In this regard, the authors witness that web-based, learning-aid resources can be valuable tools for engagement and active learning.
Research on flipped learning, understood in terms of peer-reviewed journal articles, books, and conference proceedings, is soaring from these last years on. A variety of experiences and studies can be found elsewhere with regard to the switch to online teaching and examinations because of the pandemic. Online higher education has taken a step forward, and, somehow, most lecturers are increasingly teaching online on a regular basis [50,52,56]. Instructors and administrators realized that physical attendance to classes is not linked to learning outcomes [46,48].
Some studies reflect students' dissatisfaction with online learning in general during the lockdown period, and particularly with the communication and Q&A in online classes whereas the combination of online teaching with flipped learning model has improved students' learning, attention, and evaluation of modules [44,48]. Conversely, this study has not detected such degree of dissatisfaction among students in view of the results [26,43,54]. The teaching experience acquired from the pandemic sheds light about strategies and practices to be kept after COVID times, since they are suitable to switch between blended and online classroom models [26,46,52]. Other studies show a high agreement among students that flipped teaching has promoted the development of valuable skills for their personal and professional future. These include character building, collaboration, communication, citizenship, critical thinking, leadership abilities, digital competences, and creativity [50,53].
The higher education landscape has abruptly changed as a consequence of the 2020 pandemic. Since then, students are intensifying their daily activities with technology. They have assimilated, more deeply than instructors, the key role of technology in academic life. Back to classrooms, the authors have verified the bigger presence of diversity of digital devices in face-to-face sessions, which call learners' attention even more than the blackboard or the screen. Furthermore, attendance has lessened, not strictly attributable to sanitary issues. Even more, students from a large set of universities are claiming for prerecorded classes and online exams, rather than for remote online teaching. Thus, the authors state that Internet-based tools are becoming increasingly necessary to communicate with students and to achieve more intense student follow-up: Learning Management Systems, online meeting software, e-textbooks, immediate response systems, blogs, multimedia content and repositories of web-based interactive tools, among others. These mixed tools should be designed for multipurpose activities, either face-to-face, remote, or blended, including autonomous learning.
Lastly, one remark about eventual online exams: as students are currently displaying preference and claiming for sitting online exams, it becomes mandatory for higher education authorities to issue policies and measures to tackle the difficulty of ensuring the fair assessment of learning.

Conclusions
The recent lockdown period has emerged as a chance to value the efficacy of teaching modes. The flipped teaching methods implemented by the authors during this sudden shift to remote teaching have suffered less than other classical teaching approaches, not only with regard to lectures but also to the outcomes. Lecturers struggled to take advantage of the best of the former to adapt them to a virtual context.
The procedure presented here is a suitable strategy to find a trade-off between using digital technology in engineering courses and keeping the rhythm, the quality time of classes, communicating with students and teaching staff, as well as ensuring meaningful learning. Some of the strategies and practices implemented during the lockdown period have entailed such a positive impact on the teaching practice that they have arrived to stay for the future: the tablet as a teaching instrument, pre-recorded videos with queries-to-go, repositories with questions for on-the-fly quizzes, the ability to hold online meetings among teaching unit members, among others.
Hence, an increasing concern on how to address the pervasive use of technology to achieve the effectiveness of the training system has emerged. There is a wide range for action, not only in technology but also from an ethical and holistic perspective.
The authors agree that physical attendance to classes is not linked to learning outcomes. The slight differences in passing students percentages with respect to the ordinary faceto-face teaching, their feedback on satisfaction, figures of learning outcomes, and the given step forward to digitalization in higher education can be highlighted as benefits of the actions undertaken by stakeholders. Conversely, the experience from the lockdown physical constraints has raised some controversial aspects that require further research:

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Students and lecturers' readiness to adapt to the digital transformation of higher education.

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The confidence in technology and the efficient use of digital devices to promote active learning and effective training settings. • Digital technology has influenced students' attitude, readiness, and treatment with instructors. It seems worth investigating the moments and ways students communicate among them and with lecturers during the course. • Assessment of whether higher education is lowering the standards or not. • How to design appropriate remote evaluation procedures to measure goal achievements while ensuring honesty, ethics, and fairness.