This water whistle experiment is good to do if you have 5-10 minutes spare. EC and I had a go making between finishing homework and waiting for a music lesson to start.

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You will need:

  • Straws
  • Scissors
  • Cup of water
  • Paper (optional)
  • Tape (optional)

Start by partially cutting through the straw a couple of inches from the top. You need to make sure that there is a small piece of straw left uncut to keep the two sections together.

Bend the straw (where you cut it) into a right angle. If you are doing this with smaller children then I would recommend cutting a strip of paper and folding it into a triangle. Then tape it to the straw to keep the two sections at a right angle.

Now place the long part of the straw into a glass of water.

Gentle blow into the straw, make sure that you keep it at right angles.

When you get it to make a constant sound try lifting the straw in and out of the water.

EC and I laughed so much doing this activity, we spent most of the time blowing bubbles into our glasses, but we did eventually managed to get a good strong whistling sound out.

EC tried to take it one step further and turn it into some sort of recorder by making holes in the long part of the straw.

As I said this is a short filler of an activity, but we certainly had fun doing it.

The Science Behind It

The water whistle works because the air inside the straw is vibrating. The submerged part of the straw is filled with both water and air. When you blow across the top of the longer straw segment you cause the column of air to vibrate. As this vibrates it creates the whistling sound. The pitch of the sound depends on how much air is in the straw; the more air inside, the lower the pitch. The more water you have in it, the higher the pitch will be.

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Pin for later:

water whistles: the science of sound. A fun and quick stem activity to do with children.