Woohoo! I studied Galileo so here, I can help!
Galileo made many discoveries, for example: Galileo made the first thermometer, but it wasn't very accurate. He may have dropped balls of different mass off the Tower of Pisa, but we don't know for sure. He also made his own telescope, with 6 times more magnification than the spyglass of the day!
Hope that helps :)
