Density – How closely packed together the molecules of a substance are.
Bouyancy – Ability to float or rise to the top of a liquid or gas.
Float – To sit near the surface of a liquid or gas, to not sink.
Mass – How much matter fits in a given space.
Matter - Stuff
Weight – A measure of the force of gravity on an object. Materials with more density weigh more.
Volume – How much space a substance takes up.
*****The confusing relationship between weight and mass: On earth, a bowling ball can weigh about 10 pounds. If you take that same bowling ball to the moon it will weigh much less because the graviational pull of the moon is less than the gravitational pull on the earth. Weight is a measure of gravitational pull. So the weight of the bowling ball, or anything else, changes depending on where you weigh it. The mass of the bowling bowl does not change no matter where it is. The bowling ball has the same amount of mass on earth as it does on the moon or anywhere else you take it.