Title: Plastic Bag Ice Cream
Categories: None
Yield: 1 Servings

-------------------------MATERIALS FOR CLASS OF 30-------------------------
4 qt Milk (2% or reduced lactose
-milk will work)
4 qt Whipping cream (Rich's
-non-dairy coffee creamer
-works well and is less
-expensive)
8 c Sugar
1 Bottle vanilla
30 sm Plastic ziploc bags
30 lg Plastic ziploc bags (1 gal.
-size)
30 Plastic spoons
Crushed ice
Rock salt or food grade salt
Nuts, fruit or chocolate
-syrup if desired

-------------------------MATERIALS FOR EACH STUDENT-------------------------
1 sm Plastic bag
1 lg Plastic bag
1/4 c Sugar
1/2 c (120 mL) milk
1/2 c (120 mL) creamer
1/4 ts Vanilla
1 Plastic spoon
1/2 c Rock salt (up to 3/4)
3/4 c Crushed ice

Overview: In this activity students will learn how to lower the freezing
point of water and how ice cream forms as a solution freezes. This activity
works best when students are directed to follow the instructor's
step-by-step demonstration.

Prelab preparation: Use a permanent marker to mark each plastic cup at the
1/4, 1/2 and the 1 cup levels. This will help the students when they
measure the ingredients.

Procedure: Use the plastic cup to measure 1/4 cup of sugar by filling it to
the first mark from the bottom of the cup.

Transfer the sugar into the small bag.

Fill the plastic cup to the 1/2 mark with milk. DO NOT TRANSFER IT TO THE
BAG.

Add enough creamer (1/2 cup) to the milk to bring the total volume in the
cup to the 1 cup mark.

Add approximately 1/4 teaspoon of vanilla to the milk/creamer mixture. With
smaller children the teacher may want to assist the student.

Carefully transfer the contents of the cup into the small bag which
contains the sugar. Close the bag securely.

Place the smaller plastic bag inside the larger bag.

Surround the smaller bag with several cups of crushed ice.

Pour 1/2 to 3/4 of a cup of salt over the ice and seal the larger bag
securely.

Shake bag. Be careful not to put too much pressure on the bags.

After 10 minutes check the mixture to see if it is frozen. If not, continue
shaking.

When the mixture is frozen, simply remove the smaller bag and eat the ice
cream directly from the bag. (Add nuts, fruit or chocolate if desired.)

Purpose and background: Ice keeps things cold because it absorbs heat
energy from its surroundings. The freezing point of a liquid is the
temperature at which it turns into a solid. In this activity the salt is
added to the ice; it lowers the freezing point and the ice begins to melt.

In order for the ice to melt it must absorb heat energy from its
surroundings (in this case the ice cream mixture). This causes the
temperature of the mixture to drop and the mixture freezes.

Reference: This activity was adapted from a pre-high school chemistry
activity presented by Kimberly Granatire and Phillip Murry at a ICE
Workshop at Miami University, Middletown, Ohio in July 1991.

Posted to EAT-L Digest 05 Dec 96

From: Barbara Williams

Date: Fri, 6 Dec 1996 16:12:38 -0500