States of Matter

Kathleen Moore O. W. Holmes
955 W. Garfield Blvd.
Chicago IL 60621
(312) 535-9025

Objectives:

This lesson is designed for students in grades 1 - 3.
1. To understand the meaning of the words solid, liquid, gas.
2. To provide concrete experiences with solids, liquids and gases.
3. To understand that solids, liquids and gases are all forms of matter, and
that matter is anything that takes up space and has weight.
4. To gain an initial exposure to the concept of molecules.

Materials Needed:

(for Activity #1) paper cup, zip-lock baggie filled with water, two empty zip-
lock bags, pencil, a solid object such as a rock or a ball; (for Activity #2) 3
balloons for each group: one filled with frozen water, one with water, one with
air, one scissors for each group, one empty bowl, chart paper and markers for
each group; (for Activity #3) small pieces of paper in three different colors,
one for each child in the class; (for Activity #4) vinegar, alka-seltzer or
baking soda, one-hole stopper and clear bottle, a second clear bottle, rubber
tubing (about 8 inches) or 2 flexible straws taped together.

Strategy:

Activity #1: Hold up a zip-lock bag containing the solid (rock, ball, etc.)
Introduce term "solid" Take it out. Ask children to feel it, look at it, etc.
Does it take up space? Does it have weight? Does it keep its shape? Ask for
other examples of solids, other properties of solids suggested by children;
record on chart or board. Hold up baggie with water. Introduce "liquid". Pass
around. Does it take up space? Can you see it? Does it have weight? Does it
keep its shape? (Pour water into cup so children can see that the liquid takes
the shape of its container.) List other liquids, discuss their properties,
record on chart or board. Blow air into third, empty baggie. Discuss with
children. What's in the baggie? Does it take up space? Does it have weight?
(Accept the answer"no".) Does it keep its shape? (Let air out of the bag and
ask children where it went.) Discuss other properties, other gases, if any,
that children may know the names of. Let them inhale and see how lungs expand
like a balloon. Review from board or chart properties of solids, liquids,
gases.

Activity #2: Pass out to each group the materials for Activity #2. Tell children
they are going to investigate the contents of the three balloons and write
their observations on chart paper. They will feel the frozen balloon, cut the
rubber off with a scissors. Discuss what they see and feel. Do the same with
the water balloon, observing the properties of the water both when it is in the
balloon and as they pour it into the dish or bowl. Record observations. Feel
balloon with air. Let air out. Write observations. Encourage use of
descriptive words such as "hard, invisible, wet, splashy," etc. discuss all
observations of all groups. Combine onto large chart with the three headings of
solid, liquid, gas. Try to accept all observations as valid.

Activity #3: Begin by telling the children that all matter is composed of tiny
particles called molecules. Pass out colored papers. Have all children with
"yellow" come up and demonstrate what the molecules in a solid might look like.
(Packed very tightly together; this is why a solid keeps its shape and may feel
hard). The next group of children ("blues") come up and demonstrate how the
molecules of a liquid act (farther apart' moving, which allows us to pour a
liquid). Third group demonstrates molecules of a gas (far apart: moving
rapidly)

Activity #4: Explain that children will see how another gas, carbon dioxide,
takes up space. (Gases are hard for children to deal with since they are
invisible; children will need several experiences that demonstrate that air
takes up space.) Fill one bottle to the top with water. Put baking soda or
alka-seltzer in second bottle; add vinegar, then quickly stop up the bottle with
the stopper, which has the hose or straws inserted in it. Place the other end
of the hose or straw in the bottle of water and observe the action of the carbon
dioxide as it is released in the water. (The reaction lasts for only a short
time) Discuss what happened, why, and what we learned about the gas.

Performance Assessment:

1. Use the observation charts from Activity #2
2. Ask small groups of children to play-act what the molecules in a block of ice
might look like as the ice begins to melt.
3. Have separate properties written on sentence strips or large pieces of paper.
Children must take the property-strips and put them under the headings of
"Solid", "liquid", or "gas".

Conclusions:

I had found an experiment in several books that showed how to "weigh air" I
found out that these experiments are misleading and wrong. You can't weigh air!
At least, not the way these books tell you to. So beware of "weighing air"
experiments!

References:

Science on a Shoestring Scholastic's Big Science: Matter
Return to Physics Index