What You Need:
- 2 clear plastic
- White paper
- Black marker
- Blue food coloring
- Blue marker
What You Do:
- Help your child fill the two cups with water.
- Have him place a piece of white paper in front of each cup.
- Let him use a black marker to sketch a drawing of one cup on each sheet of paper. Make sure he includes the water line in both sketches.
- Have him write "fresh water" on one paper and "salt water" on the other.
- Help your child add three drops of blue food coloring to the “fresh water” cup.
- Watch the effects of the food coloring with your child. What does he notice?
- Let him use a blue marker to sketch what he observed on the matching white paper.
- Now it's time to create salt water! Have your child add and mix about three teaspoons of salt into the second cup.
- Let him add three drops of blue food coloring to this "salt water" cup.
- Watch what happens. Does the blue food coloring interact with the salt water in the same way it interacted with the fresh water?
- Have him sketch the results on the "salt water" paper sketch.
- Which food coloring test did he like better, the fresh water or the salt water? See if your child can guess why he witnessed such different results.
The reason the food coloring distributes differently in the fresh water and salt water is because salt water is denser than fresh water. Does your child think food coloring might react differently with warm water versus cold water? Discover the answer together!