Magic Water
Teacher’s Instructions
Teaching objectives:
 Students will understand the basic properties and uses of water
 Students will demonstrate the energy difference in different states of matter
 Students will observe heat energy being used to change a liquid to a gas
Recommended Grades: K-2
Estimated Time: ½ hour
Key concepts and terms:
Surface tension: the attraction for molecules for each other on the top (surface) of a liquid
Evaporation: process by which molecules in the liquid state gain sufficient energy to become
gaseous.
Condensation: process by which molecules in the gaseous state become liquid.
States of matter: Solids, liquids, gases
Procedure:
1. Brainstorm with the class about the importance of water. What do we use it for? Why is it
important? You can talk about how the human body is 50%-80% water, the importance
of drinking, the water cycle, the possibility of water on other planets, and aquatic life.
2. Present the idea of surface tension (See Why it works for details). Set out a large dish of
water so that everyone can see the surface of the water. Sprinkle pepper over the surface.
Ask the class why the pepper floats.
3. Ask everyone to watch the pepper. Then drip a drop of dish detergent or liquid soap in
the center of the bin. Don’t squirt the soap, or the pepper will skirt away from the airflow.
Ask the class what happened to the pepper, and why. Alternatively, students can do this
experiment individually at their desks.
4. Ask the class how strong they think water is. Is it enough to break rocks? Talk about
erosion. Can water break glass? If you have the time and the resources, do the Ice Trick
(see Supplementary exercises)
5. Talk to the class about what different forms of water we see in nature. What does water
look like when it is a solid, liquid, or a gas? Tell the class about the molecules in solids,
liquids, and gases. If you have ample room, try the Solids, liquids gases activity (see
Supplementary exercises).
6. Ask the class to predict what happens when someone turns a gas to a liquid really
quickly. Go to a table or a work space with the heating device and have them surround
you, but keep them back about a foot. Add a spoonful of water to the aluminum can, and
Katy Harmon
January 2008
begin to heat it up. Continue to talk about what you’re doing. What does the heat do to
the water? What will happen when the water gets hot? Can they see steam?
7. Once the water starts bubbling and you can see steam rising, wait about one minute. Tell
everyone to stand back. In one motion, using tongs or a hot pad, take the aluminum can
and flip it into bowl of ice water, so that the mouth of the can is covered with ice.
Balance the can and take away the tongs quickly. The can will be crushed! The container
contracts because the water vapor in the can suddenly turned into a liquid.
Why it works:
Pepper demonstration
On the surface, water bonds with itself (cohesion) to make an elastic, skin-like cover. This effect
is called surface tension. The pepper floats because of its relatively wide surface area and light
weight. By adding detergent, you have weakened the surface tension in the middle of the water.
Imagine making a hole in the middle of an elastic cover, like a trampoline: the sides pull away
from the middle very quickly. Similarly, the water pulls away from the soap, taking the pepper
with it.
Can demonstration
When we heat water, it turns from a liquid to a gas. This is evaporation, and the gas is called
water vapor. A gas takes up all the space in its container and can put pressure all over its
container. A liquid takes the form of its container. If you turn gas into a liquid really fast, the
liquid can’t put the same kind of pressure on a container, and the container may even contract.
Ice Trick (Supplementary)
Water is one of a few liquids that expands when it freezes. Actually, it forms a crystal matrix
when it freezes into a solid that locks it into a specific, ordered pattern. It is not as ordered as a
liquid, and as a result, liquid water molecules can be closer to each other than ice molecules.
When the ice expands, it freezes.
Supplementary exercises:
Solids, liquids, gases: If you have a large area and moderately well-behaved students, try the
solids, liquids, gases game. Either 5 volunteers or the entire class can play this game. Explain
that when you say solid, everyone should stand extremely close together and not move. When
you say liquid, everyone can walk away slowly, but should be able to touch at least one person
nearby. When you say gas, everyone can run around quickly (but carefully!) in a larger space.
Practice a couple times, and then go from one to the other quickly. Discuss: which state had the
most energy? Which state had the least?
Ice Trick: Fill up a plastic bottle (or glass jar, but be careful!) up to the brim with water, and cap
it tightly. Place it in the freezer overnight in a bowl. When it freezes, the water will expand and
cause the bottle to break or the cap to come off.
Katy Harmon
January 2008
REFERENCES:
1.
The Incredible Can Crusher. Online:
<http://www.stevespanglerscience.com/experiment/00000043>.
Magic Water
Materials List

Large cake pan or bin filled with water
Katy Harmon
January 2008

Pepper shaker

Dish detergent or liquid soap

Heating device (hot plate or stove)

Empty aluminum soda can

Water

Spoon

Tongs for soda can or hot mitts

Large bowl of ice water
Katy Harmon
January 2008