Free PDFGrade 4 · Science · 35 min
Lava lamp
Make coloured blobs rise and fall with oil, vinegar and baking soda.
I can explain how a gas from a reaction and density make the blobs move.
A science experiment video with a free worksheet and answer key for teachers
About the video
In the video coloured blobs rise and sink in a glass of oil like a lava lamp. At home your child puts 2 tablespoons of baking soda under 150 ml oil, drips in coloured vinegar 1, 2 and 3 teaspoons at a time, and times how long the bubbling lasts.
Vinegar is denser than oil, so the drops sink, and at the bottom vinegar and baking soda react and make carbon dioxide gas. The gas bubbles carry the drops up, pop at the top and let the drops sink again until the baking soda or vinegar is used up.
What your child learns
- Explain why vinegar sinks through oil
- Describe a reaction that makes carbon dioxide gas
- Time the bubbling and compare different amounts
What's on the worksheet
- 1Predict first
- 2Time the bubbles
- 3What did you see?
- 4The science behind it
- 5Match the words
- 6True or false
- 7Float or sink in water?
- 8Lava maths
- 9Draw and label it
You need
1 tall clear glass (about 300 ml), 2 tablespoons of baking soda, 150 ml cooking oil, 100 ml white vinegar in a cup, 5 drops of food colouring, 1 teaspoon and a timer.
Safety
Do not drink it. Vinegar stings in the eyes, so wash with water if it splashes. Wipe up oil spills so nobody slips.
Tip for the adult
Pour the oil slowly down the side of the glass and wait the full 30 seconds, otherwise the baking soda clouds the oil.
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