This is a great hands on activity which demonstrates which blood types are safe to give in a blood transfusion and which are unsafe. It involves using colored water to simulate the different blood types (A, B, AB and O). Students simply mix the different "types" from a �donor� to a �recipient�. If there is no color change, the transfusion is "safe." If there is a color change, the transfusion is "unsafe". The complete assignment includes background info, materials list, step by step procedure, data chart, and five analysis and conclusion questions. My students love this lab! (I usually use this an introductory activity when teaching blood types. I have found that if it is used after they have already learned about them, the students already know all the answers!)