Science in Action: M for Molecules

Mommy Crusader Family Fun, School, Science in Action, STEAM 8 Comments

Balloons in the Snow

An exploration of molecular movement

Outside of my house, there is alot of snow.  The temperature hasn’t gotten above freezing for several weeks.  But, my husband and I spent the weekend filling hundreds of water balloons with air for our kids to play with outside. Are we crazy?  Is it cold and snowy outside? Yes, but that’s the best time to talk about how molecules slow down in the cold. So, today we went out for some fun activities with balloons in the snow.

We are watching how the warmer balloons move outside in the cold air.

Activity 1: Playing Around
This first activity explores how balloons move in the cold air and what happens when balloon touch the snow.


100 water balloons filled with air

Just dump the balloons out for the kids to play around in. My kids enjoyed grabbing the balloons and throwing them up into the air. We also kicked through the balloons, like leaves, and chased the balloons around the yard. The snow kept the balloons from popping when they were on the ground and the kids thought that was really cool!

We talked about how the snow acted likc a  cushion and kept anything sharp from puncturing the surfaces of the balloons. We also talked about how the balloons seemed to fall slower in the colder air, at first. We discussed how the air in the balloons was warmer than the outside air, so the balloons were lighter than the air around them. There were less air molecules inside the balloons because each molecule took up more space. This made the balloons lighter, so they fell more slowly. This is the same concept that makes hot air balloons work.

My preschooler is working on shaping some of the balloons now that they’d cooled a little.

Activity 2: Elastic Balloons
This activity shows how the surface of the balloons can be shaped in the cooler air.


The 100 water balloons used in activity 1

After the balloons have been played with in the cold air for awhile, challenge the children to create shapes out of the balloons.

Once the chidlren have successfully created a few shapes wth the balloons, talk about how the cold air made the air molecules trapped in the balloons move more slowly, and that made more space in the balloon itself. This allowed the surface to be stretched and shaped.

My kids enjoyed doing this a lot because of the novelty of the expereince. They really enjoyed squashing and shaping the balloons. I was surprised at how elastic the balloons were. These were water balloons, after all. We did have the occasional balloon pop, but it wasn’t as often as I thought it would be.

My first grader is giving his balloon a snow bath.

Activity 3: Shrinking  Balloons
This activity is the best example of how molecules act when they are cold. My first grader developed this activity during his own exploration of how the balloons and snow worked together. It was pretty amazing, so I thought I’d pass it along.


The same 100 water balloons used in the previous two activities.


Have every one collect one or two balloons and bury them in the snow. Set a timer for 5 to 10 minutes (depending on how cold the snow/air are).

Have the children dig out their balloons after the timer has gone off.

Talk about what has change has happened to the surface area of the balloons.

Explain that the balloons shrunk because the air molecules filling the balloons are moving much slower now than when they were put in the balloon. Talk about how when molecules move slowly they take up less space.

The air in the balloon was originally about 98 degrees Fahrenheit. This was because I and my husband blew them up and our breath was body temperature. Then the air in the balloons cooled off to about 72 degrees Fahrenheit, because they cooled off to room temperature. But that’s still a lot warmer than the 20 degrees Fahrenheit it was outside. And even that was warm compared to being buried in the snow. At each of these degree levels, the balloons shrunk a bit, but they shrunk the most dramatically with the snow bath.

For a deeper discussion about what happens when molecules get really cold check out this cool website: Chem 4 Kids.

These activities were fun ways to get outside, even though it was cold and snowy.  And as an added bonus, the kids got to run off a little of their energy that my house just simply couldn’t absorb. Just like molecules, when kids get cold, they tend to move more slowly too. It was a fun way to spend time together and learn how molecules move.


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