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SCIENCE

Dr. Tracy-ann Aston shows us how to teach your child about the environment and science at the same time with these green science activities.

Your child will love having hands-on experience with these experiments and will learn about some important science issues as they do so

Milk plastic Teach your child about the exciting world of bioplastics with this fun and messy science experiment

Plastic has poor green credentials due to being both slow to degrade and energy hungry in its production. Not all plastics, however, are created equal. Milk plastic has been around for over a hundred years and has been used to make jewellery and other decorative items. It is formed from the casein (protein) found in milk. Due to its fragility compared to regular plastic, it is not often used for products that need to be more durable.

What you need: A mug of milk (cows milk works best), four tablespoons of white wine vinegar, a heatproof bowl, a strainer or sieve and lots of paper towels.

Firstly, you need to heat the milk. This is best done on the stove so you can keep an eye on the milk. It should be hot but not boiling, think the temperature you need to make a hot, milky drink. Pour the hot milk into a heat-proof bowl and then have your child add the white wine vinegar to the milk and then stir the milk for about 30 seconds. They should notice lumps start to form in the milk. This is the milk plastic. In order to collect the plastic, have your child pour the milk through a strainer or sieve in the sink (to reduce mess) and collect the lumps. They will still be quite hot at this point so rinse them under the cold tap for a few seconds to help cool them down. When they are cool enough to touch your child can squash them together into a big clump. This clump of plastic can then be molded by kneading it until it softens and then shaping it into a desired shape. You could even add a magnetic strip or badge pin to the back of the milk plastic while it is still soft in order to make some magnets and badges. The milk plastic takes around 48-72 hours to dry completely. Leave it somewhere warm and dry for that time. When it is dry your child can paint and varnish their creation.

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'Milk plastic is used to make jewellery and other decorative items'

AUGUST/SEPTEMBER 2015 www.thegreenparent.co.uk