What it shows
A seed pressed between wet paper and the glass wall of a jar lets you watch the root come out first and grow down, then the shoot grow up and open its first leaves. Drawing it every day records how a seedling develops.
The science
Inside every seed is a tiny plant (the embryo) and stored food. When the seed takes in water it swells and the baby root (radicle) pushes out first, because the seedling needs to anchor itself and find water before anything else. The shoot comes next and grows upwards towards light. The food stored in the two seed halves keeps the seedling going until its leaves are green and can make food.
Materials
Cost: free. Many items come from home or from waste; spare parts such as LEDs, motors and wire are in the store.
- 3 rajma or chana seeds, soaked overnight
- A clean glass jar or a clear plastic bottle with the top cut off
- Tissue paper or newspaper to line the jar
- A little water
- A notebook, a pencil and a ruler
Safety
For this project: An adult must cut the bottle if one is used. Wash hands after handling wet paper and seeds.
Never use mains electricity: power models with cells, batteries or a low-voltage adapter. Sharp and hot tools, flames and lab chemicals need an adult or your teacher beside you. Keep magnets, button cells and small parts away from young children, and wash your hands after making.
All the safety rulesStep by step
8 steps. Do them in order, and test each part before you go on to the next. Write what you notice in a notebook as you go.
Soak the seeds in a cup of water overnight so that the seed coat softens.
Line the inside of the jar with folded tissue paper and press it against the glass.
Push each seed between the paper and the glass, about halfway up, so you can see it from outside.
Pour a little water into the bottom of the jar so the paper stays damp but the seeds are not under water.
Keep the jar in a warm, bright place away from direct afternoon sun.
Every morning, measure the root and the shoot with the ruler and draw the seedling in your notebook.
Add a few drops of water whenever the paper looks dry; too much water makes the seed rot.
After 10 days, plant the strongest seedling in soil and keep watching it.
What you should see
Your diary shows the root appearing on day 2 or 3, the shoot a few days later, and the first two leaves opening by day 7 to 10. A graph of shoot height against days shows how fast the seedling grows.
Viva questions
A teacher or a judge will ask how it works. Try to answer each question before you open it, then compare.
1Which part of the seedling comes out first?
The root (radicle), so it can hold the seedling and take in water.
2Where does the seedling get food before it has green leaves?
From the food stored in the seed (the cotyledons).
3Why did we soak the seeds first?
Water softens the seed coat and wakes the seed up so it can start growing.
4What would happen if the paper dried out?
The seedling would stop growing and may die, because it needs water all the time.
Take it further
Grow one jar in the dark and one in light and compare the colour and length of the shoots.
Change one thing, measure what happens, and add a table or chart of your readings: that is what turns a model into your own investigation.
Free ebooks for this project
Science projects
Easy Science Projects for Class 1 to 5
Simple, safe projects young children can make with a little help
Science projects
Biology Models Guide
Make the heart, lungs, kidney, eye, cell and more, and explain them well