Make your own lava lamp

Science concepts

Water and oil don't mix.
Oil has a lower density than water.

Special instructions

Make a fascinating lava lamp of your own.

Teachers should conduct their own risk assessment of this activity.

Class time required: 20 minutes

Materials

• Glass jar
• Water
• Food colouring
• Vegetable oil
• Teaspoon
• Jelly crystals (salt or sugar may also be used)

What to do

1. Fill the jar halfway with water and add a few drops of food colouring.
2. Pour the oil into the water until the jar is three-quarters full.
3. Wait a few moments until the oil and water are completely separated.
4. Add 1 teaspoon of jelly crystals gently to the jar and watch what happens.

What's happening?

Water and oil do not mix. They separate into two layers with oil floating on top because it is less dense than water.
Jelly crystals are denser than both water and oil, so they sink to the bottom of the jar. As the jelly crystals sink, some oil adheres to the crystals and falls through the water. The oil slowly merges until there is enough oil in one blob for it to separate from the jelly crystals and rise back up to the oil layer.