• A Mirror
• Modelling Clay
• A Nail (adult supervision)
• A Hammer (adult supervision)
• A Clear Glass Jar with a metal screw lid
• Marshmallows (use large - not miniature)
2. Place the straw in the lid and form a clay ring (air tight seal) around the straw and lid (about an inch from the bottom of the straw).
3. Screw the lid on the jar and place the short end of the straw through the lid. The clay should keep the straw from falling in. Make sure that no air can pass through the hole around the straw.
4. Take your marshmallow and draw a face on both flat sides.
5. Open the lid and drop the marshmallow in and screw the lid on tightly.
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 you stop sucking on the straw? The marshmallow is not a solid object. It has many air pockets like a sponge. By sucking the air out of the jar you decrease the pressure inside the jar which causes the marshmallow to decrease in size, 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.
Taken from Kids Science experiments