This lab is great to use as reinforcement to newly learned lessons, or it can be used as a semester review! Honestly, this is one of my favorites!* Working with a partner, students use balloons to measure the volume of a single breath of air and apply their calculations to determine (mathematically) how much second-hand smoke they breathe when exposed!* In the process of making their discovery, students use the circumference formula in a variety of forms in order to find a radius, and ultimatel