The year 5 & 6 classes learned about the density of different liquids this week and made their very own lava lamps! We were surprised to find out the oil is less dense (or lighter) than water, which is why the water separated to the bottom of the jar. The water-based food colouring that we added stayed in little droplets throughout the oil, until eventually diffusing into the water below. The final step was to add an effervescent tablet, which created gas bubbles when it dissolved, pushing the water with food colouring back into the oil in the form of little blobs.