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Description

Learn how plants 'drink' water with some special colour-changing celery.

Courtesy of The Scout Association
https://www.scouts.org.uk/activities/rainbow-celery/

Also see "Celery Colour change" activity.

Links to real world. Teaches children about how a plant absorbs water, this process is called Osmosis.

Resources

Scissors
Food colouring
Clear jars
Stalks of celery with leaves


Take it further
Use the bottoms of celery to create prints. Dip the ends into paint and decorate greetings cards in a variety of patterns and designs. This will enable you to meet requirement 2 of your Artist Activity Badge.

Safety: Science
Supervise young people, and only do science activities that are advised and age appropriate for your section. Test activities first, to make sure you’re confident you can lead them safely. Use protective clothing where necessary.

Safety: Scissors
Supervise young people appropriately when they’re using scissors. Store all sharp objects securely, out of the reach of young people

Instructions

Do plants get thirsty?
1. Everyone should think about the things plants need to survive. Do they eat food and drink water like we do? How does a plant get water?
[Plants need water to survive. Water keeps plants’ roots, stems, leaves, and flowers healthy, and stops them drying up and wilting. Plants make the ‘food’ from sunshine. Plants can get water from rainfall, being put in water, or from us watering them.]

2. Everyone should think about how plants ‘drink’ water. Where does it come in from? How can it get from one part of the plant to another?
[Plants draw water up from their roots and stems. This is done by a process called capillary action, drawing liquid upwards through smaller and smaller tubes called capillaries. Animals including humans also have capillaries. It’s what our blood runs through.]

3. Everyone should make a prediction about what they think will happen in the experiment. Will the food colouring travel through the entire celery stalk, up to the leaves, or will it collect somewhere? Which colour will most strongly dye the celery?


The celery experiment
1. Everyone should split into small teams. Each team needs a jar, a stalk of celery, a pair of scissors, and a bottle of food colouring.
2. One member of the team should carefully cut off the bottom inch of the celery.
3. Another member should fill the jar about halfway up with water, and add 15-20 drops of food colouring to it.
4. Place the celery stalks in the jars, cut end in the water, and leave them to ‘drink’. It will take around a week for them to change colour.


Observing the change
1. Everyone should gather together to compare the celery. Take them out of the jars to see the cut end, which should now be colourful. Which have changed colour the most? What does the colour at the cut end tell us about how the plant was ‘drinking’ the water?
2. Peel open the celery to see the inside. Is there any colour drawing up through its capillaries? How far did the water get in a week? Was it what you expected to see or different?

The Science- Plants absorb water through their roots through a process called transpiration. The water travels up tubes in the stems to all parts of the plants, and is used during photosynthesis to make food for the plant. When food colouring is added to the water, it travels with the water into the celery's stem and then into the leaves. Plants also absorb nutrients from the soil through the roots and up through the phloem in the plant's stems. The food colouring illustrates how nutrients are delivered to all parts of the plant.


Change the level of challenge
Try this experiment with other items and investigate how quickly they are able to draw up water in comparison to the celery stalks. You could use another living thing, such as carnations, or man-made products like paper towels. Use the same amount of water and food colouring and leave each item to 'drink' for the same length of time to make sure your results are fair.

Tags

• Celery
• experiment
• food colouring
• science
• scientist

Badge Links

• Exciting Experiments - Experiments
• Scientist - Experiment
• Scientist - Real World
• Scientist - Water