Try a plant-themed science experiment

Before you begin

• Use the safety checklist to help you plan and risk assess your activity. There's also more guidance to help you carry out your risk assessment, including examples.
• Make sure all young people and adults involved in the activity know how to take part safely.
• Make sure you’ll have enough adult helpers. You may need some parents and carers to help if you’re short on helpers.

Plant the seeds

1. Gather everyone together and explain you’ll be doing a science experiment all about seeds.
2. Ask people what seeds need to grow. Some people may already know that plants need air, light, warmth, water, and soil (which includes nutrients and minerals the plant needs – things such as nitrogen and calcium).
3. Ask what might happen if a plant didn’t have one of the things it needed.
4. Explain that each group will keep their four plants under four different conditions, to see how they grow. This is why it was important they were as identical as possible, so everyone knows any differences are because of how the plants were kept.
5. Let everyone get into groups of four and give each group four empty yoghurt pots, a watering can, a spoon, and a ruler – and enough soil and cress to fill each pot.
6. Explain how to prepare a pot of seeds. They should fill the pot about three quarters full of soil, sprinkle on the seeds, and add a light layer of soil on top. Then, they should water it.
7. Each group should prepare four pots, following the demonstration. They should make sure they’re as identical as possible to make the experiment fairer. For example, they should use the same shape pot, and use the ruler or spoon to measure the amount of soil, amount of seeds, and depth of the seeds.
8. Ask everyone to write a team name or draw something on each pot, so that they can recognise it. You could also use coloured dots or stickers. 

Prepare the experiment

1. Before placing the pots, ask everyone to label each plant with the conditions it’ll be kept in. They should label the plants ‘good conditions’, ‘no water’, ‘no air’, and ‘no light’.
2. Everyone should plan how they’ll make sure the plants get the things they’re supposed to.
   • The ‘good conditions’ plant should be kept on a sunny windowsill and given a drink of water every day.
   • The ‘no water’ plant should be kept on a sunny windowsill and not watered.
   • The ‘no air’ plant should be covered in a plastic bag that’s secured by an elastic band – but it should be kept on a sunny windowsill and watered every day.
   • The ‘no light’ plant should be kept uncovered in a dark place and watered every day.
3. Depending on the group, people may take different plants home, leave them at their meeting place, or give them to a volunteer.
4. Ask everyone about what they think will happen to the different seeds. Which do they think will grow and which might not? How might they all be different?

Next time you meet

1. Everyone should bring back their plants or collect them at the meeting place.
2. Ask the groups to judge whether their plants are healthy. A healthy plant will be standing upright with green leaves.
3. Gather together and ask each group to compare their plants. You could all discuss how they look different. The seeds kept in the dark will likely be patchy and pale, and the seeds without any water or air are unlikely to have grown at all.