Plastic? In milk? Well, sort of. You made a substance called CASEIN. It's from the latin word meaning "cheese." CasEin occurs when the protien in the milk meets the acid in the vinegar. The casein in milk does not mix with the acid and so it forms blobs. True plastics, called poymers, are a little different. If you want to make a true plastic and learn more about polymers, try the Homemade Slime experiment. Have fun!
The project above is a DEMONSTRATION. To make it a true experiment, you can try to answer these questions:
1. Will more vinegar make more casein?
2. Will you get the same results with low-fat milk, soy milk?
3. Do all types of vinegar work?
4. Will other acids, such as lemon juice and orange juice work?