After my first STEM session with Beavers (see STEM: science with Beavers) a couple of weeks ago it’s time for part 2.
Just the one activity this time, we talked about experimental methodology a bit more and then investigated what happens when you add water to oil, try to mix them and then did some cool showboating with effervescent tablets.
The set up
This experiment is really easy and simple to do. You just need some bits you probably have at home.
- A jam jar
- Vegetable oil
- Water
- Food colouring
- Fizzy tablets (alka selzter or soluble vitamins)
I brought everything we needed along with a sheet of questions and an explanation.
How to
Nice and easy and low risk, we half filled jars with vegetable oil. Then we talked about what we thought would happen when we added water. Some thought it would make foam or bubbles, some knew it wouldn’t mix because they’d done this at school.
We added food colouring to make it more dramatic.
After watching how the water and oil separated we gave the jars a good shake.
We noticed how shaking made the oil and water mix and the colour changed. Then waiting a while, the top got lighter and the bottom darker as the oil water separated again.
The fun bit
Once we’d learned the basics of mixing and separating it was time for a bit of fun. I’d brought some effervescent vitamin C tablets which I broke into small pieces (Google says this is best) and each child added a bit to a jar of mostly-separated oil and water.
We watched the bubbles rise, bringing the coloured water with them. We talked about this being another way of mixing.
The pretty results
Just cos this is a nice photo.
The green food colouring looks yellow, it isn’t great and seems to have acted as an emulsifier – must do better validation next time!
Smelly Socks and Garden Peas 