This is an advanced concept that you can teach to your young child and they can actually grasp the idea. Over the years, I have done this experiment with preschoolers and they will come to me and say to me, “My capillaries got smashed!” While the idea is a very simplistic way to describe it, they get it.
For this project you will need:
zip top bag
To show how we get bruises, wrap grapes in a paper towel and place inside a zip bag. Hit the bag with your hand and watch the grape juice spread into the fibers of a paper towel.
As you are doing the project, introduce the word “capillaries” to your child. Explain that capillaries are little blood vessels that are under our skin. Blood vessels carry blood through our bodies.
Tell them that the grapes are the capillaries.
Blood cells collect under your skin when these capillaries break. The bag acts as the skin and does not allow it to bleed outside of the “skin,” but does allow it to gather under the skin.
Have your child draw a picture of what you did. For older children, have them journal about the learning experience. Have him reenact the experiment, explaining the information to you!