I thought I'd take a look and see what they're like and as with most things Usborne, they're fantastic. So today we turned a glass of milk .......
into a solid star shape......
in just 10 minutes using these things.
1) We heated the milk gently in a pan (it didn't boil) and then added a few drops of food colouring and 2 tablespoons of vinegar
2) With a quick stir, in a few seconds it looked like this
3) We poured the solid in to the foot of a pair of tights suspended over the cup. We threw the liquid away and the left the tights in the cup for 10 minutes to drain.
4) After 10 minutes, everyone got to squeeze the remaining fluid out. We then transferred the solid lump into a cookie cutter to shape it.
5) It will take around 3 days to dry out completely and then we can decorate it.
What we've created here is plastic. We've separated the protein Casein from the milk, which has formed into a solid by changing the shape of the molecules. If you were to add rennet instead of Vinegar (or other chemicals) you'd make cheese.
This was a great little activity to round off our afternoon and it was fascinating to see the liquid become a solid. I'm looking forward to using these cards more often.