Walking Water

Have your child line up 7 glasses/cups in a row. Fill every other glass/cup with water, e.g., glasses 1, 3, 5, and 7 will have water, but glasses 2, 4 and 6 will not.

Put food colouring in each of the water-filled glasses. Use different colours in each glass if you can. If you don’t have food colouring, then use a little bit of paint or make a mark on the glass to show the water line.

Fold 6 half-sheet of paper or 4 tissue paper into a narrow strip of one inch wide. Then fold them in half lengthwise to form a “V” shape that is slightly taller than the glasses.

Ask your child to make a prediction about what will happen when the papers are inserted into the glasses.

Turn the "V" papers upside down. Take one paper and put one end in glass 1 and the other in glass 2. Take the next paper and put one end in glass 2 and the other end in glass 3. Repeat until all you reach the end of the row.

Discuss what happens when the “V” papers are inserted into the water, e.g., the papers begin absorbing the liquid.

Watch and wait what happens to the papers. The transformation might take a few minutes or it might take a few hours. What changes do you observe in the papers? What changes do you observe in the glasses? The empty glasses should now have liquid in them because the papers have sucked up the water and transferred it to the empty glass. The process is called capillary action, the tendency of a liquid in absorbent material to rise or fall as a result of surface tension.