Lava lamps

Today we looked at how oil and water don't mix. First of all we put oil and water in a jar and saw how they form layers. Next we added some washing up liquid and shook the jars to see how the soap helped to join the oil and water molecules together and allow them to mix.
We learned that this is why we need to use soap to wash properly!
We used the fact that oil and water don't mix to make our own lava lamps.
First we added water to a bottle and then filled it up with vegetable oil. We dropped some food colouring in and then came the exciting part!
We added Alka Seltzer tablets to produce a gas and when it bubbled up it took the food colouring with it, producing a lava lamp effect. We can activate them again by adding more tablets when we want to.