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Walking water
Materials
3 clear glasses, water, food coloring in two colors, for example blue and yellow, 2 sheets of paper towel, a spoon
Steps
- Put the three glasses in a row.
- Fill the first and the last glass with water. Leave the middle glass empty.
- Add blue coloring to the first glass and yellow to the last one. Stir with the spoon.
- Fold each paper towel into a narrow strip. Bend the strip in half into an upside-down V, with one end in each glass. The strip should be only a little taller than the glasses.
- Put one strip from the first glass into the middle glass, and one from the last glass into the middle glass.
- Look after a few minutes, after an hour and the next morning. What color is the water in the middle?
What happens?
Paper towel is made of lots of tiny fibers with narrow gaps between them. Water gets pulled up into the gaps. This is called capillary action. Over the edge, gravity helps, and the water drips into the middle glass. Blue and yellow mix to make green. Source: Science Buddies.
Safety for grown-ups
Put the glasses on a tray or towel, because the coloring can stain. Use plastic cups for younger kids. Don't drink the water. An adult should supervise.