Natural Elastic

[20 Minutes]

You may think of trees when you think of sap, but sap is a fluid-mainly water-found in most green plants. You can make an elastic band using
sap.

You'll need:

• sap

What to do:

1. If possible, print out these directions. Read them through together before you begin.
2. Together, gather everything you'll need and always remember science safety.
3. With your child, go outside and collect a few milliliters of sap.
4. Suitable sap can be collected from milkweed plants and dandelions. It is important never to collect sap from trees because you may damage the trees. If you break the stems or leaves of these plants, you should be able to squeeze out a fair amount of sap.
5. Help you child coat his finger with sap, to just above the first knuckle.
6. Tell your child to wait a few minutes for the sap to dry, until it is colorless.
7. Let your child gently roll the rubbery substance off his finger, like rolling off a sock. Once it is rolled off, it will be a tiny elastic band.
8. Let your child stretch the band to see if it will act like any other elastic band-but don't stretch it too much or it will break.
9. If you and your child wish, compare elastic bands made from the sap of different plants. Which ones work well and which ones don't?

Useful information:

During the spring and summer months, trees take up water and nutrients from the soil through their roots, which then are transported to the leaves. In the leaves, photosynthesis takes place and a sugary food is produced. The sugar in the leaves is then dissolved in water. Sap flows through the tree, nourishing the tree just blood running through the human body feeds the body's cells. The rubbery substance you just made is present in the plant all the time. It's in tiny pieces, which are suspended in the watery sap. As the water evaporates, the tiny pieces come together in long strands.