Egg project with my 8 year old daughter complete. We put in enough salt into a glass of water to make an egg float to the top of the cup. The reason behind the egg floating is an easy one. An egg has a higher density than regular water so it sinks. An egg has a lower density than salt water so it floats.
"Density (ISO 31: volumic mass) is a measure of mass per unit of volume."
http://wikinfo.org/index.php/Density
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My daughter did the work herself and understands everything but the definition of density and I am at a loss to put it in a way that an 3rd grader would understand.
Anyone got a good way of describing density to help me help her understand it?