First off, a note on safety. All of the following experiments are completely safe but a couple involve the standard cooking hazards: heat and boiling water. So make sure your children are always supervised in your kitchen laboratory.
Many of these experiments also have the potential to be very messy – but where’s the fun in tidy experiments?
Grow and eat sugar crystal sticks
Not only can you grow these sugar crystals but you can eat them afterwards. That’s the ideal experiment as far as I’m concerned. You can also grow sugar crystals on a string but chewing on string is considerably less appetising, so invest in a skewer or two, if possible.
To make one sugar crystal stick, you’ll need:
- A wooden skewer
- A glass or jar
- A clothes peg
- One cup of water
- Three cups of sugar
- Food colouring
- Boil up your cup of water and add three cups of sugar.
- Stir the mixture until the sugar has dissolved. This will give you sugar syrup.
- If you want to make sugar sticks in different colours, add a couple of drops of food colouring to the mixture.
- Let the mixture cool for a while, so you don’t crack your glass when you pour it in.
- Okay, now you can pour it in.
- Take your wooden skewer, dip it into the mixture and then roll it in a little bit of granulated sugar. This will encourage sugar crystals to form on its surface.
- Clip the clothes peg onto the skewer, and then lower the skewer into the glass, so that the peg lies flat across the top of the glass and the skewer is suspended, pointing downwards, and about halfway into your sugar syrup. Make sure that the skewer does not touch the side of the glass.
- Put the glass somewhere it won’t be disturbed and leave it for a few days to allow the sugar crystals to build.
- Check back so your children can see the crystals forming.
- When the sugar stick is ready, eat it and tell your children that the experiment didn’t work and that you need to try it again.
- Just kidding.
Make a rainbow in a bottle
There are two ways to try this experiment, depending on what you have in your kitchen. You can either use liquids of various densities, or you can use sugar solutions of different strengths.
The taller and thinner the jar or bottle you use, the better the final result.
For the first version of the experiment, you’ll need:
- A tall, thin jar or bottle (a small olive oil or balsamic vinegar bottle is ideal)
- 100ml of honey
- 100ml of washing-up liquid
- 100ml of water
- 100ml of olive oil
- 100ml of rubbing alcohol
- Food colouring to create five different colours
- Use your food colouring to give each of the liquids a different colour.
- The pouring requires a steady hand.
- Very carefully, pour the coloured honey into your jar and let it settle.
- Next, add the washing up liquid.
- Then the water.
- Careful now.
- Add the olive oil.
- Finally, add the rubbing alcohol and you have created a rainbow in a jar.
If you don’t have all of the above ingredients, you can use sugar and water to create liquids of varying densities.
- Get five cups and pour 100ml of hot water into each one.
- Add two sugar cubes to the first cup, three to the second, four to the third and so on.
- Add food colouring to each cup to make one pink, one blue, one green etc.
- Pour the water with the most sugar dissolved in it into the jar first.
- Add the next cup (with the second highest volume of sugar) with a very steady hand.
- Continue with the next cup.
- Behold the rainbow.
Stay in and see the water fireworks
- A jar
- Warm water
- Food colouring in different colours
- Fill your jar almost to the top with water.
- Pour three tablespoons of oil into a bowl.
- Drop small spots of food colouring in various shades into the oil.
- Mix it with a fork.
- Pour the oil mixture into the jar of water.
- Watch the fireworks appear.
Don’t leave the jar full of food colouring, oil and water unattended unless you are interested in a spontaneous, Jackson Pollock-style home makeover.
Make a bouncy egg
- An egg
- A drinking glass or jar
- White vinegar
- Place your egg in the jar and cover it with vinegar. Put it somewhere it won’t be disturbed.
- Check on the egg the following morning and top up the vinegar if necessary. You’ll see bubbles forming around it as the shell is dissolving in the acid. You may also see that bits of shell have floated to the top of the vinegar.
- Keep the egg covered in vinegar and check it after two days.
- When it’s ready, it’ll feel rubbery.
- Take it out of the vinegar and carefully wash away any remaining shell.
- You now have a bouncy egg.
A word of caution on this one: there is a raw egg underneath the membrane and if you bounce it too hard, it’ll pop and you’ll end up with raw egg everywhere.
It’s basically human nature to keep bouncing the egg until it does pop, so my feeling is that if you make the bouncy egg, you’re going find yourself cleaning up raw egg at some stage.
Write a letter in invisible ink
- Lemon juice
- A paint brush or cotton bud
- An iron, candle or hob
- Get your child to write a secret message on the paper with a cotton bud or brush dipped in lemon juice. (It doesn’t have to be a secret but I think that getting your kid to write a shopping list is a bit lame.)
- Let the paper dry.
- Choose your heating method: you can use an iron, the hob or a candle and your message will magically appear. If your child has not chosen to write something delightfully observant about your personal appearance, I’ll be surprised.
- Now it’s your turn to write a message back. Remember that you’re the adult.
For extra credit, you can use the secret letter trick towards the end of an Easter Egg or treasure hunt. Heat up the paper to reveal the final location of the treasure.
Blow up a balloon with baking soda
- A balloon
- A bottle
- A funnel
- White vinegar
- Baking soda
- First, stretch the balloon so it’s easier to blow up.
- Fix the funnel into the end of the balloon and spoon several teaspoons of baking soda through the funnel into the balloon.
- Fill the bottle halfway with vinegar.
- Keeping the end of the balloon turned over so that the baking soda is enveloped, fit the lip of the balloon over the top of the bottle.
- Lift the balloon to empty the baking soda into the vinegar.
- Swirl the bottle around a bit to get it fizzing.
You may have to experiment a bit with quantities depending on the size of the bottle you’re using. Just to clear up a common online misconception that could leave some children (and apparently some adults) very disappointed – this will only inflate a balloon, not make it magically float into the air as though filled with helium.
With thanks to super-scientists Angela and Maxwell Burton for their ideas and practical know-how.