How to Demonstrate Boyle's Law to Children
Students learn scientific concepts more fully from classroom examples over memorized formulas, according to findings from Illinois State University. For example, many learn Boyle’s Law in the same manner that it is presented on NASA’s website: “For a given mass, at constant temperature, the pressure times the volume is a constant.” Or worse, students are given the mathematical formula “p * V = C.” One way to bring this definition and formula to life to present Boyle’s law in action. Afterward, students can examine the technical aspects of the law.
Blow in to the balloon and fill it so that it will fit easily within the plastic syringe. The syringe should be 100 cubic centimeters, but the experiment will work with a 50 cc plastic syringe.
Remove the stopper on the plastic syringe.
Place the balloon in the syringe and slowly press the plunger down, letting air out of the syringe. Don't press it all the way down.
Cover up the opening on the syringe. You can use your thumb, or you can create a solid seal with duct tape.
Pull back slowly on the plunger. You're creating a vacuum, and as you do, the balloon will get bigger and bigger.
Press the plunger back down and watch the balloon get smaller. For a dramatic conclusion, pull the plunger out until the balloon pops.
- If the balloon's size doesn't change, double check the seal on the syringe.
- According to Illinois State University, one of the best practices of effective science teaching is to confront students' preconceptions. Poll your students as to what they think will occur when you move the plunger back and forth. Many will expect that the balloon will get larger when pressure is applied, and smaller when pressure is removed. Of course, the opposite occurs: Removing pressure expands the balloon to point of bursting, while adding pressure makes the balloon smaller and smaller. The reversal of their expectations will make the teaching moment more memorable.