Water Xylophone – Kids Experiment

Last week we learned how to make plastic out of milk – and it wasn’t easy! But this time around we’ve got a very simple experiment on how to make music out of water. This is the Water Xylophone experiment, a very fun and creative way to learn about sound using the following common household objects:

You will need:

  • At least 3 glasses of the same size
  • At least 3 glasses of different sizes
  • A wooden tool or utensil
  • Water of any kind


  • To set up your Water Xylophone, first prepare the glasses. What you’ll want to do is fill each one with different amounts of water. Each glass will play a different note on your xylophone, so make sure you have distinct measurements of water between each one.
  • Line up your different glasses next to each other in order of how much water is contained in each one. From there, you have your homemade xylophone. Use your wooden tool or utensil to test out the sound by hitting each glass. Is there a difference in pitch depending on what glass is hit?
  • Now let’s mix things up a bit! Swap out your glasses for ones of different sizes and repeat the experiment. How does the size of a glass affect the sound when it is hit?

The Science Bit:

With the Water Xylophone experiment done, let’s now figure out how it works! We’ve explored sound waves before, but we also need to touch upon vibrations. Vibrations cause movement in an objects surrounding air molecules. The collision of these molecules is what causes sound to occur.

In the case of the Water Xylophone, the water inside the glass vibrates when hit with the wooden tool/utensil. Since each glass has a different amount of water in it, the speed of the vibrations are different too and this produces alternate variations of pitch. For example, the glass with the most water in it vibrates the slowest and therefore, produces the lowest pitched sound.

This is how a real xylophone operates, with the longest bars producing the lowest pitched sound and vice versa for the shortest bars.