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This year’s National Science Week theme is ‘Food: Different by Design’. So let’s celebrate with some edible marshmallow slime!

Safety: When handling food, use clean hands and clean equipment. Items from the microwave can be hot – ask an adult to help.

You will need

Ingredients

• 100 grams of marshmallows
• 1 tablespoon (20 millilitres) of coconut oil
• ¼ cup (35 grams) of cornflour
• Extra cornflour for dusting

Equipment

• Microwave oven
• Microwave safe bowl
• Spoon for mixing
• Cutting board
• Measuring cups and spoons
• Kitchen scale

What to do

1. Put the marshmallows and coconut oil into the bowl.
2. Put the bowl into the microwave.
3. Turn the microwave on high for 10 seconds, then take the bowl out and stir it.
4. Repeat steps 2 and 3 until the marshmallows melt.
5. Stir everything until the oil melts completely. It will look goopy!
6. Add the cornflour and mix well.
7. Spread some extra cornflour on the cutting board, some on your mixture and some on the spoon. Then use the spoon to scoop the mixture out of the bowl and onto the cutting board.
8. Put the bowl on top of the mixture to stop it from drying out and leave it to cool for 20 minutes.
9. Before playing with your slime, you might want to dust your hands with cornflour or rub them with some coconut oil to help prevent it from sticking. The slime will gradually thicken over the next few hours until it gets tough and hard to stretch.

What’s happening?

What makes this slime so soft and stretchy? Let’s look at the ingredients to discover its secrets.

First up, marshmallows. The key ingredients in these sweet treats are sugar, gelatine and a little bit of water. They give your slime most of its stretchiness.

Gelatine is the star of the show – this protein bonds to itself when cooled, which is why marshmallows are firm. But when gelatine is heated, the bonds loosen and the marshmallows flow like slime!

Sugar also helps thicken up the mixture and helps to make it slimy. But it also makes it really sticky. Luckily you’ve added two other ingredients to combat stickiness.

Coconut oil doesn’t stick to marshmallow very well. The oil in the slime will absorb into your hands, helping them resist the stick.

Cornflour also fights stickiness. This superfine powder sticks to marshmallow but it doesn’t stick to itself. In fact, store-bought marshmallows come precoated in cornstarch or cornflour so they don’t get stuck together while they’re still in the bag.

Troubleshooting

If you find your slime getting sticky, adding a bit more coconut oil or cornflour should solve the problem. You can add these to the slime, or apply them straight to your hands.

Your slime will gradually thicken over a few hours as the oil solidifies and the gelatine forms more chemical bonds. To rejuvenate the slime, try putting it in a bowl and microwaving it 10 seconds at a time. After it liquifies, cover it and leave it to cool for 20 minutes like you did when making it.

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