This teacher sheet will provide some background information on the experiment along with the answers to the pre- and post-lab questions the students will receive.
The Five-Minute Ice Cream experiment introduces students to the science behind making ice cream and how substances can change from liquid to solid. Students follow a recipe and step-by-step instructions as laid out in the Amazing (Mostly) Edible Science book to make the ice cream. The student activity sheet asks some hypothetical questions on what would happen if they leave out a step and helps students learn why certain ingredients and steps are necessary for the experiment to be successful. Depending on the class size and flavoring you would like to use, you can adjust the ingredients accordingly. The students can have fun with the shaking step and this step can be passed around to different students. The three main components of ice cream are cream, ice, and air. The ice that surrounds the cream freezes the water in the cream and the shaking introduces air. One of the pre-lab questions touches on how ice, the solid form of water, is also a crystal and that water is less dense in its solid form due to the air pockets. The shaking step breaks the ice crystals into smaller pieces and introduces air so that the cream can flow through these pockets to give ice cream its solid yet creamy texture.
What are the three main components of ice cream? Which property of the ice cream does each contribute to?
Which ingredient forms crystals? How did the crystals form?
The water in the cream freezes into ice crystals due to the ice in the larger bag.
Which state of water, liquid or solid, is less dense (meaning it can float)? Why do you think that is?
The state of water that is less dense is the solid form. This is because as water freezes into ice, air pockets form thus allowing ice to float in water.
What is the importance of adding the salt to the bag of ice?
The salt is added to the ice bag since melted salt water is colder than solid ice water. This helps to freeze the ice cream.
In your own words, explain what is happening to the ice cream ingredients as they are being shaken.
See if they can take what they have learned about this process and explain it in their own words.
What is the importance of shaking the bag? What would happen to the state of the ice cream if you left out the shaking step?
As the ice cream freezes and forms ice crystals, the shaking breaks up the crystals into smaller pieces and introduces air into the mix so the ice cream becomes more smooth than icy. If you did not shake the bag, the ice cream would not become as solid.