Making a lava lamp and more explorations

Today we made a lava lamp. We started by putting water and oil in a bottle, once the oil had settled and stopped bubbling we added some food colouring and a berroca tablet.

The berocca tablet made it all bubbly, with the blobs of red colouring floating up and down in the water.

Once we had completed this experiment and talked about why it happened, we revisited our findings about oil and water not mixing and the reasons why.  I asked the children if they thought it would make a difference if we had more oil and less water.

The class were split, 11 believed the water and oil would mix if there was more oil and 7 believed it still wouldn't mix. 

What did we find out?

We found out that it did not matter how much water we had, the oil always sits on top of the water.