Sparking Discussion with the Cloud in a Jar Demo

Learn how to use this cloud in a jar demonstration to develop your students’ problem-solving skills and spark discussion in your middle school science classroom!

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Do your students leave class chatting excitedly about what they did or saw in the classroom? A cloud in a jar is an easy way to demonstrate cloud formation and add a little pizazz to the day.

As a teacher, I can’t pass up an activity that is both easy to prep and enhances student understanding of the content. The “oohs” and “ahhs” are an added bonus to the cloud in a jar activity!

The cloud in a jar demonstration is a simple way to explain cloud formation. Learn how to engage your students in this demo and spark higher-level thinking!

How Clouds Form

In class, I relate the formation of clouds to a recipe. There are 3 important ingredients necessary to form the cloud:

moisture,
cooling,
and condensation nuclei.

The process of cloud formation is the “recipe’s directions.”

The sun’s radiation warms the ground and this causes the air molecules to rise.
Temperatures in the atmosphere get cooler as the altitude increases. This causes the moisture in the air (water vapor) to condense and form droplets of water.
These water droplets cling to dust particles in the air which are known as condensation nuclei.
Finally, a cloud forms.

Cloud in a jar demonstration using a pickle jar. — Cloud a (pickle) jar!

Cloud in a Jar Challenge

Before the demo, I show students my pickle jar. I tell them that we are going to make a cloud in the jar and challenge them to brainstorm a procedure to make it happen! Students break into groups and begin sketching their designs.

If students are struggling to come up with ideas, here are two suggestions to help them get started:

Remind them of the three “ingredients” needed. Invite them to brainstorm what they could use to represent the moisture (warm water), cooling (ice) and condensation nuclei (smoke from a match).
You can provide them with a list of objects they can use to create the cloud in a jar. They will need ice, warm water, and matches, but I like to throw in some wild distractors as well to get them thinking!!!

Depending on the level of your students, they may be able to come up with some pretty creative and scientifically valid ways to create a cloud in a jar.

Cloud in a jar brainstorm sketches by middle school students. — Brainstorming ideas

Sparking Discussion

After students have had some time to brainstorm and sketch their ideas, I like to test a few as a class before I do the “actual” cloud in a jar demo. Usually, it takes several tries to get it right, but each try leads us closer to the answer with some well thought out prompts!

Not only is it fun to see if variables like cold water make a difference, but it sparks some really great discussion. Why didn’t this work? What could we change to improve it?

Cloud in a Jar Demonstration

This is the procedure I use for the demonstration. I love it because it uses materials commonly found in the classroom or kitchen that are easy to gather!

Materials:

Large glass jar (I like to use a pickle jar),
Hot or very warm water,
ice,
matches,
container to sit on top of the jar and hold the ice or large ziplock bag full of ice.

Directions:

Fill the glass jar about one half to one inch with hot water.
Light a match, blow it out and drop it into the jar.
Quickly put the container with the ice on top of the jar (this will cool it and keep the cloud from escaping).
A cloud will appear in the jar almost immediately.
Immediately after the cloud begins to form (and before the jar becomes fogged up), you can see convection currents forming inside if you look closely enough.

Students love to come back and take a close look at the cloud. I let them take off the “lid” and see the cloud rising from the jar. It is very simple, but it really helps them to understand the basics of cloud formation and gives them something to talk about on their way out the door!