1. Have an adult help you make a hole (the size of the straw) in the middle of the metal lid using the hammer and nail.
2. Place the straw through the hole and use the clay to make an air tight seal around the straw and lid (about an inch from the bottom of the straw).
4. Using the marker, draw a face on both flat sides of the marshmallow.
5. Place the marshmallow in the jar and screw the lid on tightly. The clay should keep the straw from falling in. Make sure that no air can pass through the hole around the straw.
6. Hold your mirror to where you can see the marshmallow in the bottom of the jar.
7. Now suck the air out of the jar making sure there are no leaks in the clay or lid.
What happens when suck on the straw? Because the marshmallow has many air pockets like a sponge, when you suck the air out of the jar you decrease the pressure which causes the marshmallow to shrink, becoming a solid. When you release the straw from your mouth the air rushes back into the marshmallow allowing it to return to its normal size.
