# Teaching and Learning Pressure and Fluids

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## Abstract

**:**

## 1. Introduction

## 2. Students’ Domain-Specific Conceptions and Reasoning in the Field of Fluids

## 3. Scientific Content: Representations and Transformation

**P**=

**F**/

**S**.

**P**is Pressure,

**F**is pressing Force, and

**S**is Surface)-half of them also present it through liquids, while the other half through solids. All of the books, with the exception of one, attribute characteristics of a vector to pressure, which is a scalar quantity, and use the expressions “exerted or accepted pressure”. Finally, the calculation of pressure on a surface, accompanied with arrows reinforcing the characteristics of a vector to pressure, appears in all of the six books.

**P**=

**d**×

**g**×

**h**,

**P**is Pressure,

**d**is density,

**g**is gravitational acceleration, and

**h**is the depth of the liquid. However, in only two of the six books do the authors use the expressions “…it has pressure…” or “…there is pressure…”, which imply that pressure is a scalar quantity. The content analysis showed that the concept of pressure is articulated and utilized in the textbooks in two distinct ways: as a vector and as a scalar quantity. This leads us to conclude that textbooks often include implicit transformations of the accepted scientific model. The main transformation is the attribution of vector characteristics to pressure, which is close to students’ dominant conception of the “pressing force model”. It would be interesting to investigate the reasons that guided the authors of the textbooks to adopt such transformations for the concept of pressure.

## 4. An Innovative Teaching–Learning Sequence for the Teaching of Fluid Related Phenomena

#### 4.1. Basic Teaching–Learning Objectives

#### 4.1.1. Differentiating Pressure from Pressing Force

#### 4.1.2. Comprehending the Compressibility of Liquids

#### 4.1.3. Classifying Both Liquids and Gases as Fluids

#### 4.1.4. Establishing the Relationship between Pressure and Pressing Force

#### 4.1.5. Enhancing the Dependence of Hydrostatic Pressure on Depth

**F**is the Force,

**P**is the Pressure, and

**S**is the Surface:

**F**=

**P**×

**S**.

#### 4.2. Selected Features of the Structure and Teaching of the TLS

## 5. Enhancing Students’ Understanding of Fluids: Selected Results

#### 5.1. Qualitative Results

#### Distinction between Pressure and Pressing Force

#### 5.2. Quantitative Results

## 6. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## References

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**Figure 1.**The two tasks/experiments that stimulate cognitive conflict in students [22].

**Figure 2.**The five tasks of the quantitative questionnaire [22].

**Table 1.**Objectives, structure content and activities of TLS, for teaching fluids and pressure, in junior high school (retrieved with permission from [12], www.tandfonline.com).

Unit/Time Duration | Objectives | Content | Activities |
---|---|---|---|

1st unit | Familiarization with phenomena Unification of fields | Experiments in the field of gases and liquids in terms of pressure Measurement of Phydr. and Patm Pressure difference causes the movement of the fluid Pressure has no direction | Discussion/performance in groups and classroom discussion Student experiments |

2nd unit | Reinforcement of weak concept (pressure) Familiarization with the experimental methodology | Variables affecting hydrostatic and atmospheric pressure Distinction of variables Experimental verification of the empirical law for hydrostatic pressure | Discussion and performance of experiments before the whole class Demonstration of Experiments |

3rd unit | Distinction between pressure and force Theory of pressing forces | Comparison between pressures/forces in a narrow/wide vessel and a small/big sucker Introduction of the relation between pressure and force | Predictions in groups and classroom discussion Demonstration and group experiments |

**Table 2.**Quantitative results [22].

POST TEST | POST-POST TEST | |||
---|---|---|---|---|

Question | Experimental Group (n = 58) | Control Group (n = 214) | Experimental Group (n = 58) | Control Group (n = 214) |

3 | 78.0 ± 10.5 | 40.0 ± 6.8 | 65.5 ± 12.0 | 25.0 ± 5.8 |

4 | 80.5 ± 10.5 | 53.0 ± 6.7 | 93.0 ± 6.5 | 43.5 ± 6.9 |

5 | 60.5 ± 12.5 | 20.0 ± 5.4 | 62.0 ± 12.5 | 0 |

6 | 83.0 ± 9.5 | 54.0 ± 6.7 | 84.5 ± 9.5 | 40.0 ± 6.8 |

7 | 71.0 ± 12.5 | 38.0 ± 6.5 | 68.0 ± 12.5 | 15.0 ± 5.0 |

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**MDPI and ACS Style**

Kariotoglou, P.; Psillos, D.
Teaching and Learning Pressure and Fluids. *Fluids* **2019**, *4*, 194.
https://doi.org/10.3390/fluids4040194

**AMA Style**

Kariotoglou P, Psillos D.
Teaching and Learning Pressure and Fluids. *Fluids*. 2019; 4(4):194.
https://doi.org/10.3390/fluids4040194

**Chicago/Turabian Style**

Kariotoglou, Petros, and Dimitris Psillos.
2019. "Teaching and Learning Pressure and Fluids" *Fluids* 4, no. 4: 194.
https://doi.org/10.3390/fluids4040194