10. The Magic Ketchup Experiment
You will need a 1 liter plastic bottle without any labels, a ketchup pack from a fast food restaurant, and salt.
Fill the bottle up with water and then add the pack of ketchup to the bottle. Make sure you screw the cap on the bottle and then squeeze the sides of the bottle. If you ketchup sinks when you squeeze it and floats when you release it, then the experiment is successful. With a little practice, you can make it stop in the middle of the bottle.
