This activity is very versatile and can be used as a warm, quiz, or group lab. I use it as a introduction to density and my density lab unit. You play a game show host of sink or float. you have ten items and you ask your players (students either individual or groups of three) will this object sink or float. They then write a hypothesis and after which you test it by dropping it in a large see through container of water. I like to play it up and really have fun with the game show aspect of it. I have one student from each group be my assistant and he or she drops the object and verifies whether it sank or floats.