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Where did the snow go?–A lesson on changes in density
K, 1, 2
Grade range: K-2
Time to complete: 45-60 minutes
Subjects/skills addressed: Science, Math
Objective: Students will change the density of powdered sugar by adding a liquid. They will use the changed sugar to decorate a snowflake cookie.
- 2 pounds powdered sugar
- Milk (2 TBSP per demonstration)
- Prebaked sugar cookies
- Colored granulated sugar
- Vanilla and butter (optional)
- Set of measuring cups and spoons
- Spoon and spreading knife
- Parchment paper
- Attached photo to accompany instructions
Words to know: measure, density, more, less
1. Ask: How do you think snow melts? What happens when it melts?
Explain that when snow melts, the density (how much space it fills) changes. The students will see how this is done by dissolving powdered sugar.
2. Direct a student to fill a measuring cup with powered sugar, making sure that the sugar is not packed into the cup. Level the top with the handle of the spoon.
Ask: Is the cup full of sugar? Let’s see if we can change that.
3. Direct a student to pour 1 teaspoon of milk into the center of the cup of sugar.
Ask: What is happening to the powdered sugar?
3. Direct another student to add a second spoon of milk. A third, etc. Observe what happens to the sugar. Use no more than a total of 6 teaspoons.
Ask: Why does it look like there is less sugar in the cup? Where did it go?
4. Repeat steps 2 and 3.
5. Stir the contents of the cup into a bowl, adding 2 teaspoons of vanilla to flavor.*
6. Create snowflakes that are 1.75″ in diameter from the parchment paper.
7. Cover the cookies with the powdered sugar icing.
8. Place the parchment snowflake on top of the cookie and sprinkle generously with colored sugar, tapping off the extra before removing the snowflake pattern. A clean pin helps remove the parchment snowflakes from the icing.
When liquid is added to powdered sugar, the sugar dissolves into the liquid, increasing the density of the sugar. The amount of air between the particles of sugar is reduced, causing the sugar to take up less room in the cup. This is similar to how the density of snow is changed when it melts. The air between the snowflakes is reduced as the snow becomes a liquid.
Snowy fact: If a snowstorm produces a light fluffy snow, then it is possible for 10 inches of snow to melt into merely 1 inch of water.
*Hint: After completing the demonstration the class can create buttercream icing that may taste better than the plain powdered sugar and milk mixture.
The file includes the image to accompany the instructions as well as print version of the instructions. [DOWNLOAD]