Boston Children's Museum
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Cooking activities are great for teaching kids how to use measurement tools, giving them a chance to apply math skills like counting, adding, multiplying, etc. In addition, when you give them a chance to design their own recipe, kids have to rely on estimation, problem solving and other science, math and engineering skills.
Ice cube trays come in many shapes and sizes. If you can find trays that make smaller cubes, they will be more effective for this activity—the larger the cube, the longer you’ll have to wait for it to freeze! You can buy ingredients ahead of time for the freeze test described below, or you can brainstorm a list with your kids one day, shop for what they come up with and conduct the experiment another day.
Gather lots of different kinds of drinkable liquids and other edible substances that seem appropriate (some foods like whipped cream and peanut butter seem sort of like a liquid and sort of like a solid—both are delicious). The more different kinds of ingredients you have, the better the experiment will be. Make sure that all ingredients are the same temperature—you can do this by putting them all in the refrigerator overnight before you use them, or leaving them all out at room temperature for a few hours. When you have all of your ingredients, separate them into several cups so that materials can be shared. You’ll want 2–3 cups of each ingredient.
Ask your students if they have ever had popsicles before. What kinds of ingredients are in popsicles? What are their favorite flavors? Tell them that you would like them to invent their own popsicle recipes, but before they do, they need to figure out what ingredients will work best. Have them brainstorm a list of ingredients they would like to test. If you’ve chosen to do the testing right away, tell your students that before they create their recipes, they’ll be testing lots of different liquids and other ingredients to see how they freeze. If you choose to have a set of ingredients that more closely resembles their brainstorm list, tell them that you’ll need to purchase their requested ingredients and that they’ll be testing these ingredients another day.
Does everything freeze at the same rate, or do some substances freeze faster or slower than others? Are there some that won’t freeze at all? Test your ingredients and find out the answer!
After you’ve placed the trays in the freezer, ask your students to predict what will happen. How long will it take for the ingredients to freeze? Will some not freeze at all? Will some freeze faster or slower? Make a list of the ingredients that they predict will be “Fast Freezers”, “Slow Freezers”, and “No Freezers”.
Keep checking on the popsicles, and have your students write down their observations. While they wait, you can have them develop a recipe to test out during the next session. Tell them that they can mix ingredients up, and that they’ll also have sugar, honey and food coloring to use. What flavors might go well together?
When the cubes are all (or mostly) frozen, have your students take them out and (if you would like) taste them. What do they notice about their popsicles—do they look bigger, smaller or the same size in the tray as they did when they were just liquid? Do they taste different or the same as they did unfrozen? Will this change their choices of ingredients for their recipes?