Questions to Ask
After placing liquids in the smaller bag…Is this ice cream yet? What do we need to make it ice cream? Why? Before shaking the bags… What do you think will happen to the white liquid? Why? When shaking…What is happening to the liquid? When eating…How does this taste? Does this remind you of anything else?

Tips for Less Mess
When shaking the bags, or rolling the cans, have towels or paper towels available for clean up of drips or spills.

Science Connection
When ice starts to melt, it is 32 degrees. This is not cold enough to freeze ice cream. Adding salt actually pushes the temperature of melting ice down below 10 degrees Fahrenheit (F). Heat flows from the ice cream ingredients to the melting ice. The melting ice warms up while the ice cream becomes cold enough to freeze. Shaking the bag does two things. It brings warmer ingredients in the middle into contact with the cold outside and speeds up the freezing process. It also makes the liquid ingredients mix with air. The air makes the ice cream soft and light—enabling this to be soft enough to eat with a spoon even though it is frozen!

Why
To be chemists—and to make a delicious treat.

What You Need

  • Quart-sized zip top plastic bag
  • Gallon-sized zip top plastic bag
  • Ice cubes
  • Salt
  • 1/2 c. half & half
  • 1/2 c. whipping cream
  • 3 1/2 T. sugar
  • 1/4 t. vanilla (optional)
  • Rubber spatula
  • Mixing spoons
  • Plastic spoons

    What to Do
    Have children place half & half, whipping cream, sugar, and vanilla, in the smaller bag. Zip bag and place inside the larger one. Pack ice inside larger bag around the smaller one. Pour at least 1/4 cup of table salt evenly over ice. Seal large bag. Now the fun begins! Manipulate and shake the bag. (Use gloves or wrap towel around outer bag. It gets very cold!) Check consistency of ice cream. If, after 15 minutes of shaking, it is not yet a solid, drain excess water from larger bag and add more ice and salt. Shake for a few more minutes. Remove ice cream bag from the larger one and quickly rinse with cold water before opening. (This removes the salt.) Taste it and enjoy!!

    Vocabulary
    Freezing: Changing from liquid to solid state when the temperature is lowered.

    Try This
    Ask the children to identify their favorite flavors of ice cream. What ingredients are needed for your family to create their favorites? Try different flavors, syrups, nuts, cut-up fruit, etc. Try making the ice cream in empty, clean coffee cans by placing the liquids and sugar in a 1 lb. coffee can. Carefully secure the top with the lid, and place the small can in a 3 lb. coffee can. Pack with crushed ice surrounding smaller can, and then pour a generous amount of salt evenly over the ice. Fasten lid of outer can. Roll can back and forth for 10 minutes. Open outer can and remove inner one. Using a rubber spatula, stir ice cream—scraping sides of can. Replace lid. Drain ice from larger can. Insert ice cream can. Pack with more ice and salt. Roll back and forth 5 more minutes or until ice cream is set. You might also want to try making ice cream without adding salt to the ice. How does this affect the process?

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