What is capillary action? Explain with this rainbow celery experiment  

Scientific concepts are best understood by kids through experimentation, especially if they are fun, quick and fast. If you have some celery lying around in your fridge, you can put them to use with this DIY experiment which teaches kids how capillary action works. This is a simple colour-changing experiment which demonstrates how liquids flow upwards in narrow spaces without any external assistance. This colourful experiment is sure to be a hit amongst budding scientists. 

What you will need  
This experiment can be performed with these easily available ingredients and materials. 

• 8 sticks of celery 
• 4 transparent glasses 
• Water 
• Food colouring of choice (preferably 4 different colours)  

Step-by-step guide 
This is a super simple experiment and does not take more than 5 minutes to set up. Remember, this can only be performed during the daytime when it’s sunny! Call your kids and help them follow these steps. 

• Fill the transparent glasses halfway with water. 
• Look for a sunny spot either inside or outside the house. Place these glasses in such a way that they are all receiving ample sunlight. 
• Next, add a drop of food colouring to each of these glasses. (It’s better to have a different colour for each glass!) 
• Cut the stalks of celery. Put around 2-3 of them in each of the four glasses. (Ensure that your kid is under your supervision while cutting the celery.) 
• Let the celery sit in the glasses for while- at least 2-3 hours. You will notice that the leaves of the celery are transforming into the colours of the food colouring.  

What exactly is happening is this experiment? 
This experiment demonstrates how capillary action takes place in a fun, colourful way. Capillary action is a process wherein a liquid flows into a narrow space without the help of, or even when it is in a position that is opposed to any kind of external forces such as gravity. It also takes place in the human body in numerous ways. For example, when water flows in and out of one’s cells and deposits vitamins, nutrients and vital blood plasma- thus keeping the body’s cells hydrated at all times.  

In this specific experiment, the celery stalks have vessels which carry through them the coloured water up to the leaves, thus making them change their colour. This is exactly how blood travels through the human body as well.