Water wicking

Objective

Difficulty:

Time: 10-15 mins

Adult supervision: possibly with set up

Dangers: scissors

To show how water can travel against gravity from one container to another

Materials

6 small containers

water

food colouring (3 colours)

paper towels

scissors

My containers are 4 cm high. My paper towel strips are 14 cm long (I cut two paper towels into quarters and used 6 pieces folded in thirds)

Instructions

Fold a narrow strip with the paper towel by folding in half lengthwise, then in half again (lengthwise). Depending on the height of your containers, you may need to refold and trim.
Arrange the 6 containers in a circle
Place the end of a paper towel in one of the containers and place the other end in an adjacent container. The ends of the paper towel should touch the bottom of each container. If the paper towel is too long, cut the paper towel to the right length.
Continue this for each paper towel and container so they are all linked.
Place a few drops of food colouring in each alternate container, then fill these 3 containers with water. There should be 3 containers without food colouring and water.
Watch as the water travels from one container to an empty one (may take a few minutes).
Do you think the water from two of the containers will make a new colour in one of the empty containers?
At the end of this activity, you can unfold the paper towels, dry them and keep them as art made from science.

Step 3

Step 5: food colouring and water added to alternate containers

The water is starting to move into the empty containers

The Science

Capillary action: the ability of water to flow through small, narrow spaces, sometimes against gravity. Paper towels are made to be absorbent. If you compare a paper towel to a normal piece of paper, what do you notice?

The fibres of a paper towel are spaced further apart compared to the tightly packed fibres of a normal piece of paper. Water can travel easier through the spaces of the paper towel.