Science Investigations For Kids: Diffusion

Water Investigations: Diffusion

As part of our science investigations for kids, we recently focused on diffusion. Diffusion is the process by which two liquids mix.

The boys enjoyed this so much as it involved two of their favourite materials - water and food colouring.

These science investigations are:

  • extremely easy to set up
  • inexpensive
  • easily cleaned up afterwards and
  • fun!

Materials Needed

Water Investigations: Diffusion
All you need are some glasses of water, a teaspoon and ...
Water Investigations: Diffusion
... some food colouring.

We only had one eye-dropper but it would have been easier to have more eye-droppers - one for each colour.

Investigation No. 1

Water Investigations: Diffusion
Using an eye dropper, place a couple of drops of food colouring into one glass of water of still tap water.

Water Investigations: Diffusion
Watch the movement of the food colouring as it diffuses into the water, swirling and turning. It's actually very beautiful.

Water Investigations: Diffusion

Investigation No. 2

Water Investigations: Diffusion
What happens when you add two separate colours?

Investigation No. 3

Water Investigations: Diffusion

This time, use a teaspoon and stir the water to make a whirlpool before adding any food colouring.

Look at how the water concaves, becoming higher on the sides and lower in the middle. This happens because the water in the middle is moving faster than the water at the sides. The water in the centre has less pressure than the water at the edge. The atmospheric pressure is therefore able to depress the water in the centre more than at the edge.

Water Investigations: Diffusion

Once the water is moving swiftly, add some drops of food colouring. What happens? How does the food colouring react differently when added to moving water? Is the process of diffusion speeded up or slowed down?

Investigation No. 4

Water Investigations: Diffusion
Time to add some tea leaves. This is really interesting as the tea leaves don't dissolve but move with the motion of the water.

Water Investigations: Diffusion

Stir the water and watch what happens to the tea leaves. Do they move to the outside of the glass as you'd expect due to centrifugal force? Or do they gather together in the centre of the glass at the bottom?

Investigation No. 5

Water Investigations: Diffusion
Lastly we used a larger container of still water to drop droplets of food colouring in. With more space, we could watch the food colouring move around for longer.

These investigations were heaps of fun. We'll be doing them again for sure!

Have you played with water lately? I'd love to hear about your experiences.

You may also like these activities:

Mixing Coloured Water
Mixing Coloured Water
Seed Matching Game
Seed Matching Game

Return to the Articles List for other children's learning activities or children's book reviews.

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