Tamika inflates and ties off a balloon in her classroom and then takes it outside on a cold, winter day. Immediately, she notices that the balloon has gotten a little bit smaller. Why does this occur?

Because when air is warm, it expands, and when it gets cold, it contracts. Assuming that the heat is up in the classroom on a cold winter day, then the air in the ballon must be warm. As soon as Tamika takes the balloon outsides, the warm, expanded air turns cold and should contract. This is why the balloon got a little bit smaller.