Kitchen Science Experiments for Kids
Kitchens are well stocked laboratories. Acids, bases, oils, salts, surfactants and a heat source are all present, along with measuring equipment and a sink. The experiments below have been picked for a specific reason: they work first time, they use ordinary ingredients, and none of them will ruin an afternoon with clean-up. They are ordered roughly from tidiest to messiest.
Quick answer
The kitchen science experiments worth doing on a wet afternoon are the ones that use things already in the cupboard, produce a result within a few minutes, and do not leave the floor sticky. Milk and washing-up liquid, red cabbage indicator, dancing raisins and a lemon battery all qualify. The ten below are grouped by how much mess to expect, with the science explained for each.
Key takeaways
- Most reliable kitchen experiments rely on density, surface tension, acids and bases, or gas production.
- A tray under everything turns most of these from messy into tidy.
- Red cabbage indicator is the single most versatile thing you can make at home.
- Never mix cleaning products; stick to food ingredients.
- Change one ingredient and re-run to turn an activity into an experiment.
Set up once, then run several
A large baking tray as a work surface, a jug of water, kitchen roll and a bin bag will contain nearly everything below. Set out all the ingredients before you begin. Most of these take under five minutes, so it is worth doing three or four in a session and comparing them.
Almost no mess
1. Dancing raisins
Drop a few raisins into a glass of clear fizzy water. They sink, collect bubbles, rise, lose the bubbles at the surface and sink again, cycling for several minutes.
The science: raisins are slightly denser than water so they sink. Carbon dioxide bubbles cling to their wrinkled surface, and enough bubbles make the raisin-plus-bubbles combination less dense than the surrounding liquid. At the surface the bubbles pop and the cycle restarts. Try a smooth grape for comparison â it does not work nearly as well, which tells you the wrinkles matter.
2. The floating egg
Put an egg in a glass of tap water; it sinks. Stir several tablespoons of salt into a second glass and the egg floats. Pour fresh water gently on top of salt water and the egg will hover in the middle.
The science: dissolving salt increases the water's density without much increasing its volume. Once the liquid is denser than the egg, the egg floats. The suspended egg in a layered glass is the memorable version.
3. The self-inflating balloon
Put two teaspoons of bicarbonate of soda into a balloon using a funnel, pour a few centimetres of vinegar into a bottle, stretch the balloon neck over the bottle without letting the powder fall in, then lift the balloon upright.
The science: the acid and the carbonate react to produce carbon dioxide gas. The gas has nowhere to go but the balloon. This is the volcano experiment without the mess, and it gives a measurable result â balloon circumference â if you want to compare quantities.
A little mess, contained by a tray
4. Milk and washing-up liquid
Pour whole milk into a shallow dish, add a few drops of food colouring in separate spots, then touch the surface with a cotton bud dipped in washing-up liquid. The colours race away from the bud and keep swirling.
The science: milk contains fat and protein, and its surface has a tension holding it in an even skin. Detergent molecules break that tension where they land and bind to the fat, and the resulting movement drags the colouring along. Skimmed milk gives a much weaker effect, which makes a good follow-up test.
5. Red cabbage indicator
Chop red cabbage, cover with boiling water, leave for ten minutes and strain off the purple liquid. Pour a little into several clear glasses and add different household substances.
| Add this | Roughly | Colour shift |
|---|---|---|
| Lemon juice or vinegar | Acidic | Pink or red |
| Fizzy water | Slightly acidic | Reddish purple |
| Tap water | Near neutral | Unchanged purple |
| Bicarbonate of soda | Basic | Blue or green |
| Washing soda | Strongly basic | Green to yellow |
What red cabbage indicator shows
The science: the pigments in red cabbage change shape depending on the acidity around them, and different shapes absorb different colours of light. This is exactly how laboratory pH indicators work. Keep the leftover liquid in the fridge â it lasts a few days and can be used to test anything else in the house.
6. The lemon battery
Roll a lemon to break up the flesh inside, push a galvanised nail into one side and a copper coin or wire into the other, and connect the two to a small LED or a multimeter.
The science: two different metals in an acidic liquid set up a chemical reaction that pushes electrons from one to the other. The lemon is not stored electricity; it is the electrolyte that lets the reaction proceed. One lemon rarely lights an LED, so wire three or four in series â discovering that is part of the experiment.
7. Invisible ink
Write on white paper with a cotton bud dipped in lemon juice and let it dry completely. Warming the paper â an adult holding it near a lamp bulb or using a hairdryer on hot â makes the writing appear brown.
The science: the juice's compounds break down at a lower temperature than the paper does, browning before anything else on the page. Adult supervision is needed for the heating step.
Worth the clean-up
8. Cornflour slime
Mix cornflour with water at roughly two parts to one until it resists a fast poke but drips through your fingers when held still.
The science: this is a non-Newtonian fluid. Its thickness depends on how quickly force is applied â sudden pressure jams the suspended particles together, gentle pressure lets them slide past each other. Dispose of it in the bin, not the sink, where it sets hard.
9. Oil, water and colouring
Half-fill a jar with water, top with vegetable oil, and add drops of food colouring. The colouring sinks through the oil in beads and bursts into the water below. Add a piece of effervescent tablet for a slow lava-lamp effect.
The science: oil is less dense than water and the two do not mix, because water molecules attract each other strongly and exclude oil. Food colouring is water-based, so it passes through the oil untouched and disperses on contact with the water.
10. Baking soda and vinegar, done properly
Rather than building a volcano, run it as a measurement. Use the same amount of vinegar in each of several identical bottles, vary only the amount of bicarbonate of soda, cap each with a balloon and compare how big the balloons get.
The science: the same acid-carbonate reaction as before, but now with a variable and a measurement. You will find that adding more powder stops making a difference at some point â the vinegar runs out. That plateau is a real chemistry lesson and far more interesting than foam on the table.
Making one of these into an experiment
An activity becomes an experiment when you change one thing on purpose and record what happens. Does the raisin cycle slow as the drink goes flat? Does whole milk really outperform skimmed, and by how much? Does a thicker cornflour mixture resist a poke more? Write down the prediction first, run each version a few times, and see whether the numbers agree with the guess.
