This activity is taken from: https://www.messylittlemonster.com/2020/04/magic-paper-towel-art-science.html
Marker (permanent and washable)
Paper towels
Water in a small tray
Scissors
Prepare your paper towels. Do this by taking a square of paper towel and folding it in half. Then cut the paper towel so you end up with a small square with another small square behind it.
Now it's time to design your pictures. Take a permanent marker and draw an image on the top layer of the folded paper towel. Start by drawing a simple design like a rainbow, you can always get more adventurous as you get into it!
When you lift up the top layer of the paper towel you will see that the pen has gone through the paper towel onto the layer below. Now it is time to colour in this outline or add to your image. Colour the image with washable markers so the colour bleeds when it is put into water.
Now its time for the magical part of this paper towel activity. Make sure everyone is watching as this happens fast! Place the paper towel into the water. As the water soaks through the two layers of the paper towel the colours from the bottom layer will appear through the top layer of the paper towel making it look as if the colours or images have appeared by magic.
What do you notice happening when you place the paper towel in the water?
Draw more pictures and experiment with the technique.
Can you write words on the bottom layer? What happens when you place it in water?