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Our bodies contain thousands of miles of blood vessels. Enough to circle the earth 2 1/2 times if laid out end-to end! Arteries and veins are the main throughway for blood to carry cells. But in between veins and arteries are these tiny vessels called capillaries. Capillaries only can allow red blood cells to pass in a single-file line! This experiment helps to illustrate how blood cells are able to fit through the tiny capillaries.

• 3 big glass jars
• A sink or big mixing bowl
• Salt
• Box of wallpaper paste
• Water
• Food coloring
• Petroleum jelly (like Vaseline)
• A funnel (with a 19 mm tube)
• Bath beads

1. Before you start, try to push the bath bead through the funnel– if they go through, then the funnel you are using is too big for this experiment.
2. Now, fill the jar with 2 cups of cold water, and add 3 tbs. of salt and a few drops of food coloring. Next, Fill a second jar with 2 cups of hot water. Add 3 tbs. of salt and a couple of drops of red food coloring.
3. Mix 1 cup of wallpaper paste with 2 1/4 cups of water in the third jar. It will be lumpy like mashed potatoes.
4. Now, soak the bath bead in one of the mixtures. Try to see if it will fit through the funnel. Does the temperature of the water affect the feeling of the bath bead? Does applying Vaseline on the bead help it slip through the funnel? What happens when you soak the bath bead in the wallpaper paste solution for 20 minutes or so? Does the bead take on a different shape? Which solution causes the bead to become more fragile?