Air Pressure Curriculum

Section 3—Lesson 5: Contrasting Linear and Relational Causality in Explaining Air Pressure Phenomena

Understanding Goals

This lesson draws students' attention to the relational causality involved in many pressure-related phenomena. Students are engaged in an activity where air pressure acting on both sides of a bag influences whether students can push or pull on the bag.

Subject Matter

• Differences in air pressure can cause effects. Areas of higher pressure move towards areas of lower pressure until equilibrium is achieved.
• A change in the amount of force or the area over which that force is applied results in a change in air pressure.
• 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

• Air pressure-related phenomena are often best explained using a relational causal model.
• In a relational causal model, what happens is due to a relationship between two variables—often a relationship of balance or imbalance.
• Most people lapse back into a linear model of thinking about cause and effect, and this can make it hard to understand how air pressure acts.
• 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 a better explanatory fit.