As children begin to consider different types of matter, a fun way to point out differences in matter and weight is to experiment with whether items sink or float. This activity will give help children think about the compositions and densities of objects.

set up ideas:
A large water table is best for this activity, but a large tub that is transparent can also be great for observing objects that sink or swim. The important thing is that every child can see and interact with the tub.

let's get started

For this sink or float activity, you will need a large water table or clear tub, several items that can safely be placed in the water for the experiment (e.g., utensils, cup, blocks, etc.), a science journal and crayons or pencils for recording your results.

step 1
Fill the water table or clear tub with an ample amount of water. Place the items available for testing onto a tray.
step 2
Draw a line down the middle of a journal page. Label one side of the split page as the float side and the other as the Sink side.
step 3
Hypothesize which items will sink and which will float by drawing a picture of each item on either the float side or the sink side.
step 4
Conduct an experiment and see which items float and which items sink to the bottom. Compare the results with the children's hypotheses. Did anyone get them all correct?

Discuss the materials that the items being tested are made of, as well as how heavy they are and their sizes. After performing the experiment, what conclusions can they draw about the types of materials that sink and the types that float?
Tips and Tricks Tips and Tricks
Ensure that each child plays a helpful role by letting them take turns placing and removing items from the tub or water table. Make sure that you have a towel nearby to clean up any splashes.
Follow Up ActivityFollow up Activity
With what they now know about objects that sink and float, have the children create their own boats and other floating vehicles using craft materials such as foam and craft sticks.