In the 1990s, classes throughout the United States began participating in Classroom FeederWatch, sending data on birds they had seen at feeders in their schoolyards to the Cornell Lab of Ornithology. The launch of eBird in 2002 opened up new possibilities for submitting data on all types of bird species, allowing users to record and upload information on species they have seen or heard. The database currently contains over 500 million observations, representing every country and almost all of the world's more than 10,000 bird species. In any location--urban, suburban, or rural--students can observe birds and share data through the eBird citizen science project. By submitting data to eBird, students join hundreds of thousands of citizen scientists throughout the world providing crucial support for professional scientists. Engaging students in investigations related to birds meets the "Framework for K-12 Science Education" goal by piquing their interest in relevant real-world science and opening a window into options for careers in fields ranging from ecology to computer science. This article examines how students have learned by participating in the eBird program and gives examples of lessons teachers have created using it.