What we needed:
Clear containers, effervescent tablets (we used alka seltzer), food colouring, vegetable oil, spoons.
First, we made several predictions:
1) We predicted what would happen when we dropped an effervescent tablet into a jar of water.
Result: We found that it fizzed up and dissolved.
2) We then predicted what would happen when we put a few drops of food colouring into water.
Result: The food colouring mixed with the water and the water changed colour.
3) We put some oil into a container and predicted what would happen if we were to drop an effervescent tablet into it.
Result: The tablet did not dissolve in the oil and instead remained in tact and sank to the bottom.
4) We then predicted what would happen if we tried to mix oil and water.
Result: The oil did not mix with the water but instead floated on top of it as oil is denser than water.
5) Our final prediction was to see what would happen when we put a few drops of food colouring into the oil and water.
Result: The food colouring did not affect the oil but instead sank through it and coloured the water beneath.
Finally we were ready to make our lava lamps. Here’s how we did it:
1) We used our Maths skills to measure a quarter of the capacity of the bottles we were using. We then filled it with that amount of water.
2) We then poured double that amount of oil in.
3) We then chose what colour we would like to use and carefully poured several drops of food colouring into the bottle.
4) We waited for the food colouring to mix with the water. For some people it took a long time for the food colouring to sink to the bottom!
5) Finally we dropped half of an alka seltzer tablet into our bottles.
Results: The alka seltzer began dissolving in the water causing coloured bubbles to ‘erupt’ throught the oil.
We thought our lava lamps were beautiful and were very happy with them!
We wrote about our lava lamp experiments. Here is a sample of our work.
Link to Maths:
Strand Unit: Capacity