Heart rates can be determined by the amount of physical activity your body is engaging in. The more physically active you are, the faster your heart beats. You can measure the rate your heart is beating by taking your pulse. This science...

There's a lot of talk these days about fit kids. People who care (parents, doctors, teachers, and others) want to know how to help kids be more fit. Here are five rules to live by, if you're a kid who wants to be fit.