```States of MatterKathleen Moore                 O. W. Holmes                               955 W. Garfield Blvd.                               Chicago IL 60621                               (312) 535-9025Objectives: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 #22. 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

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