Water Balloon Science Experiment

Kids love playing with water, which makes learning from water experiments so interesting and exciting. How can we make it even more fun? How about adding some water balloons to our science? Children in preschool through grade 6 will enjoy this water balloon science activity.

My kids have been obsessed with experiments exploring the properties of water lately. In a recent science fair my son did a presentation on “does it float” and played with a variety of different concepts. Since we have already done quite a lot of flotation experiments and water projects for kids, I knew I was going to have to come up with something unique and different to capture their imagination. When I came up with the idea to use water balloons, I knew I had hit a home run! My kids absolutely loved this water balloon science experiment and keep asking to do it again and again.

Density Science Project

The idea is to explore what liquids float, and which ones sink, by filling water balloons with different liquids.
water balloon science project

What do I need for this water experiment?

  • A large container filled with water. Look for something with a depth of at least double the size of your water balloons when they are filled. Deeper is even better!
  • Water balloons
  • 60mL Syringe
  • Different liquid solutions (some ideas: water, vegetable oil, corn syrup, salt water, sugar water, juice, etc.)
  • Permanent marker

Doing the experiment

I highly recommend you do this activity outside. Water balloons are very easy to pop! I also recommend you fill multiple balloons with each type of liquid. That way if one pops you have some back ups.

One note of caution: We found vegetable oil tended to weaken our water balloons making them more prone to popping. We did not experience this with any other liquid type, only vegetable oil.

Water balloons are meant to be filled under pressure. Using the syringe you can easily fill the balloons. We found a 60mL syringe made perfect, egg sized water balloons. Simply wash well after each type of liquid so you don’t cross contaminate.

Here are some ideas for what to put in your balloons:

  • lamp oil
  • rubbing alcohol
  • vegetable oil
  • dish soap
  • milk
  • maple syrup
  • corn syrup
  • honey
  • salted water

Filling the balloons with a syringe is a fantastic fine motor strengthening activity, but prepare them outside or in an easy to clean up space, as it can get messy.
using a 60mL syringe fill the water balloons with various different liquids to perform the density experiment

As you fill each balloon make sure you label it so they don’t get mixed up.

Once your balloons are filled, head over to your container. This is the perfect time to ask for some predictions. Will it sink or will it float? Then place your balloons in the water and watch what happens.

The science behind this water balloon experiment

Different types of liquids have different densities. In this experiment we are able to see which liquids have a greater density than water causing them to sink, and which ones are less dense than water, which allows them to float.

Science Projects for Kids

Shelley is a former communications manager with a BSc in Psychology specialization. Since starting a family ten years ago, she has been a full-time writer in both fiction and non-fiction, and on her site: STEAM Powered Family. She is passionate about quality education and childhood mental health, and last year started homeschooling her two children who both have special needs. Follow along on FacebookPinterestTwitter and Instagram.

Beth Gorden
Beth Gorden

Beth Gorden is a homeschooling mother of six who strives to enjoy every moment with her kids through hands-on learning, crafts, new experiences, and lots of playing together. Beth is also the creator and author of 123 Homeschool 4 Me where she shares 1000+ free printables, creative homeschool lessons, crafts, and other fun ideas to help preschool and homeschooling families have fun while learning and exploring together.