Walking water rainbow

How to make it

1. 

   1

   Line up the cups

   Put 6 cups in a ring or a row.

2. 

   2

   Fill every other cup

   Fill cups 1, 3 and 5 nearly to the top with water. Leave 2, 4 and 6 empty.

3. 

   3

   Add the colors

   Add red to cup 1, yellow to cup 3 and blue to cup 5. Use 5 or 6 drops each.

4. 

   4

   Fold the bridges

   Fold each paper towel lengthwise into a strip about 2 in wide. Bend each one so it dips into 2 cups next to each other.

5. 

   5

   Watch it climb

   Check every 30 minutes. The color climbs the towel and drips into the empty cups. Red and yellow make orange.

6. 

   6

   Talk about why

   Paper towels are full of tiny gaps. Water sticks to the fibers and pulls itself up through the gaps. That's called capillary action, and it's how plants drink.