Wednesday, January 15, 2014

Floating and Sinking Balloons

It is always fun to find new ways to explore the concept of floating and sinking.  I love it when you find an activity that allows you to reduce and control your test variables, so that you are not throwing everything into the water to see if it floats or sinks.  This activity explores if balloons filled with air or water would sink or float in water.  We originally saw the inspiration for this idea over at Teach Preschool.

To setup the experiment, I filled three yellow balloons with increasing amounts of air and three green balloons with increasing (and similar) amounts of water.  Then, I filled a large bowl with water.  I also had two balloons (one of each color) completely empty.  Bug was excited to get started.  Before each step I asked her to guess what was going to happen to each balloon.

The two empty balloons floated much to her surprise.  She then took the next pair of balloons (the smallest filled balloons).  We discussed how they felt different - which one was heavier and which one was lighter.  Again I asked her to guess what would happen when we put it in the water.  She guessed the yellow (air) would sink because it was larger.

She was amazed when it floated.  She then correctly guessed the green would sink because it was heavier. We continued working through balloons of increasing size.  She correctly hypothesized that the heavier one would sink each time.  She was also highly amused at mommy acting out the water molecules when they saw a big green balloon coming.  

The large balloon filled with water was very heavy for her to lift, and it made a big splash when she put it in.

We also took some time to make sure that the balloons that floated were given some attention as well.  We stopped to see how they barely touched the water.  She even tried throwing them at the water and they bounced right off!

We continued to play and explore.  Bug really liked pushing balloons under the water and letting go to see what would happen or comparing balloons of different sizes.

You may see some markings on the side of our bowl in the above picture.  To find out more about an activity related to those markings, sign up for the littleblast newsletter before January 24th.

Also, I left everything out after we were done and Little Bear (18 months) discovered it after her nap. Although I don't have any pictures, I can tell you that she had a lot of fun dropping balloons into the water.  She was soaked by the end from all the splashing!

Overall this was a great activity to introduce how the mass (how heavy) the object was affected if it would sink or float in water.



  • 8 balloons (4 each of 2 different colors)
  • Large bowl with water (big enough so that the balloons don't touch the bottom)
  • Towel to cover your work surface if you are doing this inside


  1. Take your first color of balloons and fill with differing amounts of air.
  2. Take the second color of balloons and fill with differing amounts of water (match the size of the air balloons as close as possible).
  3. Invite the child to drop different balloons into the water.   Ask them to guess if it will float or sink before they drop it in.
  4. Have fun!


1 comment:

  1. We also did this in the bath and the girls had so much fun! It was much easier and less messy with the little one this way.


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