There are hundreds of satellites in orbit around Earth. Readily available data about them can be a treasure trove for investigations by students at all levels. Orbital parameters and energy changes can be explored. Many of these satellites transmit signals that can be detected by an inexpensive radio receiver--a scanner--designed to receive FM transmissions from local emergency networks, airports, and various public service broadcasts. The investigations described below were carried out with a scanner purchased for $15 at a flea market. No modifications were necessary because the standard antenna is capable of receiving signals from satellites with a ground track passing by within 1000 km. Table I lists just a few satellites that transmit easily detected signals. Other satellites and frequencies used can be found at various information pages on the internet.