Students can make thousands of fascinating observations just by roaming around in nature or doing experiments with everyday items. Citizen science involves collecting that data and analyzing it as part of a collaborative project. Some of the tools on this list get students observing the behavior of animals on a webcam, listening to and analyzing the sounds of whales, watching the stars in the sky, and identifying plant or animal species. Often students are given the chance to work with -- or at least give the data to -- real-life scientists. These websites and apps seed ideas for fun, safe experiments and encourage students to actually try them to benefit the greater good.