4 Rainy-day Science Experiments

4 Rainy-day Science Experiments

Give your kids something fun (and educational) to do on those rainy spring days.

By: Alyssa Chirco

We all eagerly await the arrival of spring — sunshine and warmer weather give us more time to play and explore outdoors. But don’t let a grey, wet spring day stop you from having fun with your kids. You can even use a gloomy day to teach them a bit of science in the process. Whether you put on your raincoats and head outside or stay indoors where it’s nice and dry, these rainy-day science experiments are perfect for some family fun.

Tip: Rainy-day experiments can get a little … wet. Keep a roll of absorbent Bounty Paper Towels to soak up watery messes.

Experiment 1: Measuring Precipitation

Exactly how much rain is falling? Find out by making a rain gauge to measure the precipitation.

Clear 2-liter plastic bottle
Serrated knife
Heavy bucket or flowerpot
Waterproof marker


  1. Using a serrated knife, cut about 10 centimetres off the top of the plastic bottle (a grown-up should do this step!)
  2. Flip the top of the plastic bottle upside down to create a funnel
  3. Secure the funnel inside the opening of the plastic bottle using waterproof tape
  4. Measure and mark centimetres on the bottle using a ruler and a waterproof marker
  5. Set the bottle inside a heavy bucket or flowerpot and place on a flat, open surface

Measure the precipitation in your rain gauge at any time. Consider checking it daily, and having your kids chart the daily rainfall — just like the meteorologists do!

Experiment 2: Making Rain Indoors

Before your kids unleash the garden hose indoors, note that this experiment demonstrates how rain forms. Although this “indoor rain” doesn’t come from clouds, it helps illustrate what causes water to fall from the sky.

Ice in an ice tray
Shallow pot
Oven mitts


  1. Bring a pot of water to a boil
  2. With oven mitts on, hold an ice tray over the steam
  3. Watch as “rain” forms and falls from the bottom of the tray

How does the science behind this work? The surface of the ice cube tray is so cold that it cools the steam, turning it back into liquid form. Explain to your kids how water can exist in three different states — liquid, solid or gas — depending on its temperature.

Experiment 3: Creating a Rainbow

If the sun comes out after the rain has ended, don’t miss the opportunity to create your own rainbow.

Sheet of white printer paper
Glass of water


  1. Hold a glass of water above a sheet of white printer paper
  2. Angle the glass so sunlight passes through the water, forming a rainbow of colour on your paper

This is actually similar to how rainbows form in the sky: Light refracts when it passes through raindrops and is separated into the colours red, orange, yellow, indigo and violet. For even more fun, have your kids hold the glass and the paper at different heights and angles to see how their rainbow changes. Kids can also use the rainbow as a “stencil” to create their own effects on paper with markers or coloured pencils.

Tip: Clean up crafting messes — like marker and crayon marks — on your hard surfaces with a Mr. Clean Magic Eraser.

Experiment 4: The Doppler Effect

Introduce the concept of radar by conducting a simple experiment. Get your kids to make a hypothesis about what will happen before you perform the experiment.

Electric razor
Microphone or a sound-recording device (such as a smartphone’s voice memo function)


  1. Turn on a recording device
  2. Turn on an electric razor and hold it either close or far from the microphone
  3. Bring the razor closer or farther from the microphone
  4. Listen to the recording

The change in the sounds you hear as the razor is moved closer or farther away is known as the Doppler effect, or the change in the frequency of the sound. By measuring these frequency changes, forecasters can use the radar to predict weather patterns in your area. After completing this experiment, your mini meteorologists will have a better understanding of how weather forecasting works.

Instead of feeling like you’re stuck indoors on a rainy day, take advantage of the wet weather and have some fun with these experiments. It’s a great opportunity for your kids — and you — to learn something new.

Alyssa Chirco is a St. Louis-based freelance journalist who provides writing, editing and social media services for print, web and small businesses. She writes about parenting and family life for STL Parent.


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