By Francesca Vidal
With summer vacation here, there is no better way for kids to spend their summer then exploring their natural curiosity through STEM activities. This summer, enjoy making ice cream and a bottle rocket while also learning about freezing point depression, emulsions, and reactions!
Ice Cream
Ice cream is a fun treat for kids of all ages to enjoy during summer. Though making ice cream may sound complicated, it is actually pretty simple. This STEM activity is one of our favorites as along with being able to eat ice cream, this activity also does a great job of teaching kids about chemistry.
Materials
Measuring spoons
Measuring cup
1 tablespoon of sugar
½ cup of half-and-half (milk or heavy whipping cream can instead be used)
¼ teaspoon of vanilla extract
½ cup of salt
8 cups of ice cubes
2 pint or sandwich Ziploc bags
2 gallon Ziploc bags
Oven mittens
Timer
Steps:
In both pint or sandwich Ziploc bags, add ½ cup of half-and-half and ¼ teaspoon of vanilla extract. Tightly seal the bags.
In the gallon Ziploc bag, add 4 cups of ice cubes and ½ cup of salt.
Grab one of the smaller Ziploc bags and place it inside the gallon Ziploc bag. Seal the gallon Ziploc bag.
Wear oven mitts and shake the gallon Ziploc bag for 5 minutes.
Add 4 cups of ice cubes to another gallon Ziploc bag and place the other small Ziploc bag into this gallon Ziploc bag. Close the gallon Ziploc bag.
Wear oven mitts and shake the gallon Ziploc bag for 5 minutes.
Enjoy your ice cream!
How it Relates to STEM:
When you are done making your ice cream, you should have two bags: one with solid ice cream and another with liquid ice cream. The solid ice cream was able to become a solid due to the addition of salt (without salt, the ice cream cannot reach a temperature cold enough to turn into a solid). The salt was able to lower the temperature and melting point of that bag of ice cream, causing it to feel colder than the other bag and melt faster. This process of being able to lower the melting point is called freezing point depression. Freezing point depression occurs when a solute is added into a solvent. Solutes can also increase the boiling point of solvents. The more solutes that are added, the bigger decrease in melting point and increase in boiling point will occur. Freezing point depression works because without the solute, molecules are able to go from a liquid state (molecules are a bit spread apart) to a solid state (molecules are organized in a lattice structure) easily. However when a solute is added, the solute molecules make it difficult for the molecules of the solvent to organize themselves into a lattice structure, causing the melting point to decrease. Also, making the ice cream also caused an emulsion to be made. Emulsions are when two liquids that typically do not mix well together mix. Fat and water usually do not mix well; however the fat in the half-and-half and water were able to mix in order to produce the ice cream.
Bottle Rocket
Blast into summer by creating a rocket using household materials! This fun STEM activity would be most enjoyed by kids 7 to 12 years old. Parent supervision is recommended especially for younger kids to ensure the reaction that causes the water bottle to lift is executed correctly.
Materials:
Scissors
Tape
4 paper straws
1 liter plastic bottle
Wine cork
Paper towel
2 tablespoons of baking soda
1 cup of vinegar
A funnel
Materials (markers, construction paper, etc.) to decorate your rocket with
Steps:
Grab the plastic bottle and decorate the bottle however you want to turn it into a rocket.
Orientate the water bottle so that the tip of the bottle is at the bottom of the rocket.
Add 4 straws at the bottom corners of the bottle so that the water bottle can stand by itself.
Flip the water bottle so that the tip of the bottle is facing upwards.
Using a funnel add 1 cup of vinegar to the bottle.
On a paper towel, place 2 tablespoons of baking soda and fold the towel into a tight tube.
Go outside and place the paper towel in the tip of the bottle so that the baking soda goes inside of the bottle.
Quickly loosely secure the tip of the bottle using a wine cork and flip the bottle upside down.
Watch the rocket take off!
How it Relates to STEM:
The reason that the rocket is able to lift off the ground is due to the chemical reaction that occurs between the vinegar and baking soda. When vinegar and baking soda are mixed together, carbon dioxide is created. Carbon dioxide fizzles, causing the explosion to occur. Furthermore, the small hole in the tip of the water bottle causes the water bottle to go higher because the carbon dioxide gas is easily able to be forced out of the bottle.
Works Cited
McClelland, Sarah. “How to Make a Water Bottle Rocket.” Little Bins for Little Hands, 27
May 2022, littlebinsforlittlehands.com/rocket-water-bottle/.
Science Buddies. “Make Ice Cream in a Bag.” Science Buddies, Science Buddies, 31 May
2014, www.sciencebuddies.org/stem-activities/ice-cream-bag.
Comments