Physical And Chemical Changes

Carolus Love Hoyne School
8905 S. Crandon
Chicago Il 60617
(312) 535-6425
Objectives: Grade 2 1. The students will identify some physical changes of matter. 2. The students will identify some chemical changes of matter. 3. The students will distinguish between physical and chemical changes. 4. The students will classify changes as physical or chemical. Materials Needed: skim milk liquid detergent microwave vinegar hot plate salt baking soda white bread straws toaster toast sauce pan molded ice water cookie cutters bundt pan pyrex bowls pictures plastic cups/tops whipping cream Duncan Hines Cupcake Mix 2-glass bowls orange juice letters aluminum foil poster boards tape glue markers measuring spoons strainers large spoons flour Strategy: Introduction Discuss the meaning of the word change. Give examples. You were in first grade last year and now you are in second grade. Turn the television to another channel when you want to see a different program. Elicit other examples of what change means to them. Activities 1. Show the students a ball of play dough. Ask who can tell me what this is. Allow students to take turns manipulating the play dough into various shapes by using cookie cutters. Ask the following questions: Did it change into a new substance? Is it still play dough? This is called a physical change. 2. Demonstrate the proper way to make a bubble. Pour bubble solution into foil pan. Place the straw in the pan and blow into the straw. The team who blows the biggest bubble within 30 seconds is the winner. Is it still a soap solution? Therefore, this is a physical change. 3. Observe ice change from a solid to a liquid and then to a gas (steam). Put a piece of ice into a pot and set it on the hot plate until it melts, then set a piece of aluminum foil over the pot. Students will explain what they observed and draw pictures to illustrate how the ice changed. Although the ice changed from one phase to another, it is still water and can return back to the solid state again. 4. Demonstrate how butter is made. Empty a 1/2 pint of whipping cream into a plastic container and take turns shaking it. Observe how it looks, sounds and feels. Pour off the milk and put a pinch of salt in it. If I melt the butter and pour it back into the liquid and stir it, can we get the whipping cream back? Their response should be yes. This is another physical change. You can sample the butter on crackers or bread. Strategy: Define chemical change as when matter is changed into something new or a different substance. Activities 1. Demonstrate the procedure for making glue. Put a pint of skim milk and six tablespoons of vinegar into a glass sauce pan and heat slowly, stirring continually. When the milk forms small curds, remove it from the heat. Pour off the liquid. Dry the curds. Then add 1/4 cup of water and a level tablespoon of baking soda and stir. What did you notice? They should have noticed some bubbles. Is it still milk? Is it still baking soda? Is it still vinegar? Is it still water? Since we do not have the same materials we began with, this is called a chemical change. 2. Students will observe the difference between a piece of toast and a plain slice of bread. If you scrape the brown material from the bread can you make the brown material white again? Try and see if it can be done. Since we can not do this, it is a chemical change. 3. Demonstrate making orange soda. Fill a glass 1/2 full of water and the other half with orange juice. Add 1/2 teaspoon of baking soda and 1/2 teaspoon of sugar. Work in groups to make your soda. Ask the same type of questions with each substance as in previous experiments. This is a chemical change. The bubbles formed carbon dioxide which was caused by a chemical reaction. 4. Teacher and assistant will help students in preparing cupcakes. Examine the cupcake mix before and after it was cooked. How did it look? Did it change? The baking powder is what caused the cupcakes to rise. Is it still flour? Is is still baking powder? Is it still water? Their response should be no. Therefore, this is a chemical change because we have a new substance formed. Performance Assessment: 1. Given pictures of various physical and chemical changes, students will put them under the correct heading on the chart. 2. The students will demonstrate their understanding of changes by explaining the difference between physical and chemical change. References: Vancleave, Janice Pratt. Chemistry For Every Kid. John Wiley and Sons, Inc.
New York: 1988.

Walpole, Brenda. Science Experiments to Amuse and Amaze Your Friends. Random
House, New York: 1988.

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