Air Pressure Curriculum
Section 3—Lesson 7: Reasoning About Air Pressure Differentials Using Relational Causality
Understanding Goals
This lesson forces students' attention to the relational causality involved in drinking from a straw by offering cases with modifications that illustrate how a linear causal model falls short.
Subject Matter
- A change in the amount of force or the area over which that force is applied results in a change in air pressure.
- Air pressure is dynamic, not static.
- Differences in air pressure can cause effects. Air from areas of higher air pressure moves towards areas of lower air pressure until equilibrium is achieved.
Note to Teacher: It is important not to substitute the word 'changes' for 'differences' here. If both sides of the relationship change in proportion to each other, then it will still be at equilibrium.
- When the air pressure within an object and the outside air pressure are equal or balanced, it is difficult to notice the effects of air pressure. When the air pressure within an object and the outside air pressure are unequal or unbalanced, we are more likely to notice the effects of air pressure.
Causality
- Using a relational causal model is important for understanding a variety of scientific phenomena, including many which have to do with air pressure.
- Most people tend to lapse back into a linear model of thinking about cause and effect, and this can make it hard to understand pressure-related phenomenon.
- When our current models do not explain our observations of a phenomenon, we need to re-evaluate either our model or our observations. Often, we need to discard our current model for a model with better explanatory fit.
