This walking water experiment is so easy and your kids will love it. It is a great way to teach them how capillary actions works. Capillary action (sometimes called capillary motion or capillary effect) is the ability of a liquid to flow in narrow spaces without the assistance of, or even in opposition to, external forces like gravity.
This spontaneous rising of a liquid is the outcome of two opposing forces- cohesion (the attractive forces between similar molecules) and adhesion (the attractive forces between dissimilar molecules).
Why is capillary action important? Without capillary action, our blood wouldn’t circulate through our body. Trees wouldn’t be able to draw water into their roots and distribute it to their leaves. Simply put, life wouldn’t exist without capillary action.
Here is what you will need:
- 5 clear glasses
- Blue, yellow and red food coloring
- Paper towels (4)
Fill 3 of the glasses with water. Add a few drop of blue food coloring into one jar, yellow in another and red in the third.
Arrange the glasses in a row so that they are in this order: blue glass of water, empty glass, yellow glass of water, empty glass, red glass of water.
Take a piece of paper towel and fold it so that it is in a skinny strip. Then connect the glasses with the folded paper towels.
The water will start moving quite quickly. The paper towel will draw the water upwards against gravity and then into the empty glass beside it.
Here is where you can teach a secondary lesson. Ask your kids what color they will get if they mix blue and yellow. How about yellow and red?
As the colored water mixes into the empty glass, a new color will appear. When the water is finished “walking” there will be a beautiful rainbow!
This experiment moved a lot faster that I expected (about 20-30 minutes). Once the water levels are perfectly equal in each glass, the experiment is complete.
If it helps to watch a demonstration of this walking water experiment, check out this great example by Science Buddies:
This walking water experiment is such a fun and simple way to teach kids about capillary action. My kids loved making a rainbow of colors and even learned about mixing primary colors. Give it a try and let me know how it goes!