MnSTEP Teaching Activity Collection > MnSTEP Activities > Cartesian Diver Race

# Cartesian Diver Race

#### Summary

In this lab, students will have to build a Cartesian diver to bring to class to race. I do this as an introduction to the gas laws, specifically Boyle's Law which deals with volume and pressure of gas at the same temperature. The students bring in their cartesian diver and we have a bracketed tournament to see whose cartesian diver can beat the competitor to the bottom of a 5 gallon Culligan jug.

## Learning Goals

I want them to have to think about how they would construct their diver in order to be successful.

## Context for Use

The tournament is the start of the unit on gas laws. I tell them to have a cartesian diver in class in three days. I don't tell them what it is, only that it will be a tournament to see who can construct the fastest. Word gets out the next day and kids have an idea of what it is. Its a great opportunity to discuss which ones worked/didn't work and why. How could the divers be altered to be faster? Would it be faster if it has large bubble or small bubble. Do you want a dense material? How does it work?

Subject: Chemistry:General Chemistry:Gas Laws, Physics:Thermodynamics & Statistical Mechanics:Gas Law
Resource Type: Activities:Lab Activity, Classroom Activity

## Description and Teaching Materials

On the day the divers are due, they place their cartesian diver in five gallon water bottle that Culligan gave to me. If your school has a water dispenser in the teacher lunchroom or office, you can just borrow one of those. We race them two at a time through a tournament bracket. When we get to the final four, we go through some questions together. How do these work? What's happening inside the diver? What's happening inside the jug of water? What's the relationship between pressure and volume? Several questions similar to these to get them to think about how these work. Bracket for Cartesian Diver Tourney (HTML File 22kB May6 11)

## Teaching Notes and Tips

Can be used in either a block system or a skinny (50 minutes) class period. It doesn't take much prep time except to get a large bottle that has a secure cover and fill it with water. A two liter bottle would work too if you don't have a larger container. The kids get excited about showing off their diver. If there is an opening in the brackets, the teacher can compete too. The trick is to have a large bubble in the diver so that it shrinks more when pressure is applied. When the tournament is done, we discuss the relationship between pressure and volume. Is the relationship a direct or indirect relationship between pressure and volume.

## Assessment

There isn't any formal assessment. Its an activity to start out the gas laws. They get excited about it and I think the concept of Boyle's Law sticks with them.