What it shows
Rubbing a crayon over paper laid on a leaf prints its vein pattern. Grass, banana and wheat leaves show parallel veins; peepal, mango and hibiscus leaves show a branching net, and the pattern tells you which group the plant belongs to.
The science
Veins are the leaf’s pipes: xylem brings water up from the roots and phloem carries sugar made in the leaf to the rest of the plant. The veins stand out as ridges, so a crayon rubbed across the paper prints them. Plants with one seed leaf (monocots, such as grasses, maize and banana) have parallel veins; plants with two seed leaves (dicots, such as mango and peepal) have a net-like pattern of branching veins.
Materials
Cost: free. Many items come from home or from waste; spare parts such as LEDs, motors and wire are in the store.
- 10 to 12 fallen or spare leaves of different plants
- White paper or old notebook pages
- Wax crayons with the paper peeled off
- Glue or a stapler to bind the album
- A pencil for labels
Safety
For this project: Pick only fallen leaves or ask an adult before plucking. Wash hands after collecting leaves.
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.
Collect leaves of as many different shapes as you can find, including at least one grass and one broad leaf.
Lay a leaf on a hard table with its rough underside facing up, where the veins stick out most.
Place a sheet of paper over it and hold it still with one hand.
Rub the side of the crayon gently and evenly across the paper until the whole leaf shape appears.
Write the plant name under each rubbing, asking an adult or teacher if you are not sure.
Sort the rubbings into two piles: parallel veins and net veins.
Bind the pages into an album with a cover and a contents page listing the two groups.
Add one page explaining what the veins do for the leaf.
What you should see
An album of clear vein prints sorted into two groups, showing that leaf veins come in two main patterns and that plants can be grouped by them.
Viva questions
A teacher or a judge will ask how it works. Try to answer each question before you open it, then compare.
1What do veins do in a leaf?
They carry water into the leaf and food out of it, and they hold the leaf flat.
2Name a plant with parallel veins.
Grass, maize, banana or wheat.
3Name a plant with net veins.
Mango, peepal, hibiscus or tulsi.
4Why rub the underside of the leaf?
The veins stand out more on the underside, so the print is clearer.
Take it further
Look at the seeds of the same plants: parallel-veined plants usually have one seed leaf and net-veined plants have two.
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
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