We saw this idea on Irresistible Ideas For Play Based Learning. Check it out ( http://www.playbasedlearning.com.au/2011/10/floating-sinking-and-predicting/)
Before we started this fun science lesson, we talked about the words float and sink. First of all I was truly amazed that my newly turned three year old Tasbeeh read the words float and sink to me when I asked him what did the words say on the index card! He totally took me by surprise and I needed a minute to recover lol
After telling them what the words means and quizzing them on it, I asked the boys to find three objects in the house that we will see if it floats or sink. After they ran around the house, I picked three of my own and then we met up to discuss what we had and whether it looks like it will sink or float.. prediction time.
The boys filled our bin with water as far enough to make a difference that we could see what sank and what floated.
The boys took turns placing objects in the water and telling me if it floats or sinks and this helped them to keep the definitions in their memory.
We laid down on the floor to get a better look at the items that went to the top and the ones that went to the bottom. It was fun and afterwards our four yr old journaled about it, writing his new vocabulary words float and sink and then drawing in his journal what happened with our wet and fun science experiment.