After School Science.
The first round of After School Science, ‘Crazy Chemistry’ finished with students sharing their learning with their parents and siblings. The students conducted investigations, explaining the steps they followed and what they discovered – not before asking their parents what they thought would happen.
The enzyme investigation (which involved eating chocolate) seemed to be the most popular, followed very closely by the making of Goon Goo (i.e slime!!).
Density Investigation photos
The second round of After School Science, ‘Fabulous Forces,’ started Week 5 (20-05-10). The students have begun by designing and making a 10 Second Marble Machine. In this activity students must design and make a machine which will keep a marble moving for 10 seconds. This sounds easy until you roll a marble across a room and see how little time it takes. The machine can only be made out of recycled boxes, tubes, plastic bottles, cardboard, paper and tape. Once the marble is dropped into the machine no one is allowed to touch it or the machine. The students are finishing off their machines and testing will begin next week. Who will be triumphant? We will keep you posted! Winners to be announced at the assembly on Monday! 🙂
Below is the recipe for Goon Goo so you can make your own at home with your family.
If you add more of the borax solution the goo will clump together and make a bouncy ball.
2 tablespoons of PVA (white) glue
2 tablespoons of water
1 drop of food colouring (optional – can result in stained hands and clothes)
Borax Solution: (Needs to be made ahead of time so that it can cool.)
1 tablespoon of borax (found in laundry section of supermarket)
1 cup of warm water
* If you put this in an old labelled drink bottle you can keep what is left over.
Once the water and borax are in the bottle, shake vigorously until the borax is dissolved.
1 clear cup
measuring spoons (or a tablespoon & a teaspoon)
spoon for stirring
1. Combine the glue and water in the cup. Stir until they are completely mixed.
2. Add 1 drop of food colouring to the glue-water mix (anymore will cause your (anymore will cause your goo to stain whatever it touches!)
3. Add the borax solution a teaspoon at a time, stirring well after each one. The mixture will start to form a blob. Keep stirring. If some of the glue-water mix does not clump together add a little more borax solution.
4. Pour out the excess liquid, put the blob in a plastic bag and knead it.
5. Remove the blob and play with it!
This plastic polymer feels cool and clammy. It looks wet and sticky, but will snap if you pull on it quickly. It will bounce if you throw it on the ground, and slump into a puddle if you put it on the table.
How it works:
PVA glue contains 2 kinds of polymer: polyvinyl acetate and polyvinyl alcohol. The polyvinyl acetate Is in the form of microscopic drops and the polyvinyl alcohol surrounds the drops. When you use glue to stick things together, the polyvinyl alcohol dries up, which causes the polyvinyl acetate particles to clump together and become hard. When the borax solution is added to the glue-water mix, it forms lots of rubbery ‘bridges’ that link the polyvinyl chains. That is why you end up with a blob. This kind of chemical reaction is called “cross-linking.”