Part 1: Making Ice Cream!

Materials: For 1 serving of ice cream

● Sugar (1 tablespoon)

● Half and half (milk or heavy whipping cream works too) (½ cup)

● Vanilla extract (¼ teaspoon)

● Salt (table or rock salt will both work) (½ cup)

● Ice cubes (4 cups)

● Small sealable bags (2 bags)

● Gallon-size sealable bags (1 bag)

● Towel/oven mitts

● Timer/clock

● Measuring spoons and measuring cups

● Serving spoon or spatula

Procedure:

1. In one of the small sealable bags, add 1 tbsp of sugar, ½ cup of half and half (or milk or

heavy whipping cream) and ¼ tsp of vanilla extract. Seal the bag well.

2. In the large gallon-size bag, add 4 cups of ice and a ½ cup of salt (table salt or rock salt

should work).

3. (Optional)

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Place the small bag with your ice cream mixture inside the second small

sealable bag. This helps prevent salt from seeping into your ice cream mixture.

4. Then place these two bags (make sure they are well sealed) inside the gallon size bag of

ice and salt.

5. Shake the bag well for 5 minutes. The bag can get pretty cold so wrap the bag in a towel

or use oven mitts to shake it up. Check on the texture of the ice cream mixture over the 5

minutes. What does it feel like after 1 min? After 3 min? After 5 min?

6. After 5 minutes, your smallest bag should be full of ice cream! Use a spoon or spatula to

scoop it out and serve with your favorite toppings. Enjoy!

Note: This is the recipe for vanilla ice cream, but if you want to make other flavors, check out

this table. Use the base recipe above and add the following to the small bag in the first step for

chocolate, mint chocolate chip or strawberry ice cream.

Ice Cream Flavor

Additional Ingredients

Chocolate

1 tablespoon unsweetened cocoa powder

Mint chocolate chip

1 tablespoon mini-chocolate chips

¼ tsp peppermint extract

Strawberry

1 tablespoon chopped strawberries

Activity extensions:

● What happens if you don’t add any salt to the bag of ice? Is there a difference in how

cold the ice is? Or were there different amounts of ice that melted?

● Is there a difference if you use rock salt versus table salt?

What’s happening?

What is happening to our ice cream mixture? How does it turn from a liquid mixture to ice cream

in just 5 minutes without a freezer? The key to this experiment working is the salt. Salt is able to

change the properties of the ice in the bag. We know that ice typically freezes at 32 degrees

fahrenheit. This temperature is known as the freezing point

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of ice, which is just a fancy term for

the temperature at which something freezes. Salt has the unique ability to lower the freezing

point of ice. This means that ice will not freeze at 32 degrees, it will stay liquid and freeze at

lower temperatures.

What temperature the salty water freezes is dependent on how much salt is in the water. This is

why road crews sprinkle salt on the roads during winter storms. When the temperature drops

below 32 degrees, the salt helps the ice remain liquid and protects us and our cars from slipping

in temperatures below 32 degrees.

But you might be wondering why ice melting causes our ice cream mixture to get colder. This is

because for ice to melt, it needs energy.

Ice is basically a group of water molecules that are stuck together. This is similar to how we

stick Legos together to form a new structure. For the ice to melt and those water molecules to

separate, it will take energy, just like how breaking those legos apart takes some energy. So

where does the ice get the energy to melt? Well, heat is actually a form of energy. So the ice

takes heat or energy from the ice cream mixture to melt the ice in the bag. This works in our

favor because the more heat that is taken from our ice cream mixture, the colder it gets and the

more frozen it becomes, turning our milky mixture to a frozen yummy treat! So to summarize,

the salt helps the ice melt faster and the more the ice melts, the faster the heat is taken from our

ice cream mixture and the more frozen our ice cream becomes.

Part 2: Ice Fishing

Materials:

● Ice (whole cubes, not crushed ice from a fridge dispenser)

● Glass of water

● A small bowl, cup, or dish

● String or yarn (about 1 foot)

● Salt (Kosher iodized works best, don’t use chunky sea salt)

● A small stick (optional)

Procedure:

1. (Optional)



Tie one end of the string around the stick so it looks like a little fishing rod!

2. First, pour cold water into the bowl until it is mostly full

3. Add at least one icecube to the water. Try doing one cube to start, and then when you

learn the technique do lots of cubes to see how many you can get!

4. Dip the string in the water so it is wet

5. Lay the string across the ice cube that is bobbing around in the water.

a. Notice how if you were to pick up the string, the ice cube would not stick to it and

would remain in the bowl.

6. Take a pinch of salt and sprinkle it where the piece of string is laying across the ice

cube.

7. Wait about 20 seconds for the salt to melt the ice and then refreeze around the string

8. Gently pick up the string, and the ice cube should be pulled with it out of the bowl!

Activity extensions:

● Try repeating this with lots of ice cubes in the bowl. Lay the string across each one,

sprinkle each cube with a little spot, and wait 20 seconds just like before. Pull up your

string gently, how many ice cubes can you get on the string at one time?

● Try varying the amount of salt. What happens if you use only a tiny pinch? What about a

big spoonful?

What’s happening?

We previously learned about the phenomenon known as freezing point depression. A

dissolved solid like salt in water will cause it’s freezing point to be lower. This means a little bit of

salt sprinkled onto ice will cause it to melt much faster. The top of the icecube where the string

is will melt a little bit. However, we only added a small pinch of salt, not enough to melt the

whole ice cube. That little bit of water on top of the ice cube will then re-freeze around the string,

attaching them together!

If there’s too much salt present, the ice cube will melt but not be able to re-freeze. If there’s too

little salt present, it won’t melt the ice cube enough to create a layer of water over the string.