Turn ordinary PVA glue into silly putty!
This is a fun activity with lots of science involved. The long molecules in the glue are linked together by the borax, making a solid - but the links can move, so the solid can flow like a liquid.
I taught high school chemistry for many years and this was always one of the most popular practicals we did!
Step 1: What You Need
4% Borax solution
A disposable container (eg plastic cup)
A plastic spoon
Put about 15 ml (1 tablespoon) PVA glue in your container and add an equal quality of water and a few drops of food colouring. Mix with your plastic spoon. Add about a teaspoonful of talcum powder and stir.
Now pour in a teaspoonful of 4% Borax solution and stir . The mixture should immediately go thick and stick to the spoon. Lift up the solid and start kneading it. Keep working it until it is smooth and not sticky. You can wipe your fingers on paper towel to help.
Now play with your putty! You can mould it into a ball and it will bounce a little. If you leave it to stand, it will flow into a puddle like a liquid. If you try to move it quickly it will break in two.