Experiments and Books

Great experiments to try at home

Empty glass trick

Materials: A paper towel, a glass, a bowl filled with water

  1. Stuff a paper towel tightly into the bottom of a glass. It should stay there even when you turn the glass upside down.
  2. Fill a bowl with water.
  3. Turn the glass upside down. Hold the glass very straight and plunge it into the water.
  4. Slowly count to ten. Lift the glass out of the water without tipping it.
  5. Pull the paper towl out of the glass. Is the paper still dry?
The paper towel in the glass stayed dry because water couldn't get into the glass. Why not? The glass was already full of air.



Strong Air

Materials: A glass half filled with water, an index card or piece of cardboard

  1. Fill the glass halfway with water.
  2. Put the cardboard over the top of the glass.
  3. Hold the cardboard tight against the glass.
  4. Turn the glass upside down while holding the cardboard in place. Keep the glass straight.
  5. Take your hand away from the cardboard.
What happened? Air pushes up, down, and sideways on everything it touches. This pushing power is called air pressure. The air pushed up on the cardboard more than the water and air inside the glass pushed down. This kept the water from falling out.



Balloon blow-up

Materials: Balloon, small funnel or straw, spoon, baking soda, vinegar, small juice or soda bottle

  1. Stretch the balloon, so that it will be easy to blow up.
  2. Use the straw to put two large spoonfuls of baking soda into the balloon.
  3. Half fill the bottle with vinegar.
  4. Stretch the neck of the balloon over the neck of the bottle. Don't let any baking soda fall in.
  5. Hold the balloon up so that all the baking soda falls into the vinegar in the bottle.
What happened? When baking soda (a solid) and vinegar (a liquid) get together, they produce a gas called carbon dioxide. The gas takes up more room than there is in the bottle, so it blows up the balloon!



Raisin race

Materials: Clear glass jar, plastic spoon, ginger ale, raisins

  1. Place the glass jar on a flat surface such as a table or countertop.
  2. Carefully pour the ginger ale into the glass. *If you tip the glass and pour the ginger ale gently down the side, you will keep more of the fizz in the liquid.
  3. Drop two raisins into the ginger ale. Watch them race up and down.
  4. Use the spoon to remove the raisins. Squeeze one of them to flatten it. Now drop both raisins back into the ginger ale. Does one raisin go up and down faster than the other?
  5. Put a bunch of raisins into the ginger ale and watch them race.
What is happening? Ginger ale has a gas called carbon dioxide dissolved in it. A machine pumps the gas into the soft drink at the factory, and then the lid is sealed. When you open the drink, the hiss you hear is the gas escaping. As the gas comes out of the spaces between the molecules of liquid, it sticks to the raisins. When there are lots of bubbles, they lift the raisin to the surface. There the bubbles break and the raisin sinks again.



Oil and Water

Materials: 1/4 cup water, 1/4 cup vegetable oil, a small glass, food coloring

  1. Pour the water into the glass.
  2. Add a couple of drops of food coloring and mix.
  3. Add the oil. What do you see? Which layer is on top?
  4. Tightly cover the glass with plastic wrap.
  5. While holding the glass over the sink, shake the glass so that the two liquids are thoroughly mixed.
  6. Set the class down and watch what happens. Do oil and water mix?
Oil and water do not mix. The oil layer is on top of the water, because of the difference in the density of the two liquids. The density of a substance is the ratio of its mass to its volume. The oil is less dense than the water, so it is on top.



Girls' Science Investigations is funded by the National Science Foundation.