observing each object in water measuring the size of each object calculating the weight of the objects comparing the shapes of the objects
I gave my students this multiple choice question: Which method below would be the best way to determine if an egg, plastic foam, a piece of wood, or a candle would float on water?

Only one answer is correct among these 4 choices:
- observing each object in water
- measuring the size of each object
- calculating the weight of the objects
- comparing the shapes of the objects

Could you tell me which one is correct?

observing each object in water