Stepping Into Science is a series where we explore exciting science concepts from A-Z. There will also be activity ideas accompanying each post to extend your child’s learning.
Your neighbourhood ice cream cart uncle fervently ringing his bell is your favourite sound in the world on a sweaty afternoon. You always order the winning combo: “One Raspberry Ripple on rainbow bread, please!”
Once he passes the ice cream to you, you barely have time to devour the treat with your eyes before it vanishes into your stomach. Luckily for you, the bread absorbed any melted ice cream.
But why does ice cream melt?
Why does ice cream melt?
Ice cream is made of air pockets, ice crystals, and milk fat, among other ingredients. Once ice cream is taken out of the freezer, it begins to melt. The more air pockets trapped in the ice cream mixture, the faster the ice cream melts. When the ice crystals in the ice cream melt, the frozen air pockets and fats shift and begin moving around, which explains the melting we see.
Ice creams with greater milk fat content will melt slower because the fat clusters can stay together even when the ice crystals begin melting. Ice creams with lesser milk fat content will have more air pockets and ice crystals, speeding up the melting process.
Now that we know how and why ice cream melts, we can compare it to other things that we know melt quickly – like ice cubes!
For this activity, you will need:
What to do:
1. Fill one cup with ice cubes, and the other cup with ice cream. Make sure to do this fast!
2. Take down the starting time. The race begins!
3. Leave the cups beside each other in the same location and room. Monitor the melting progress every 5 to 10 minutes.
When it looks like the contents of one cup have completely melted, stop the time! You can stir the contents with the spoon to check if everything has truly melted.
Which one melts faster – ice cubes or ice cream?
Ice cream contains gas (air pockets), liquids (melting ice crystals)and solids (the milk fat clusters), while an ice cube is made of only solid water. Heat loosens the structure of liquids and gasses more quickly than that of solids, causing the ice cream to melt first and win the race!
You can try pitting one flavour of ice cream against crushed ice, or different flavours of ice cream against each other. What do you think will happen?
Make your own ice cream
Did you know you can make your own ice cream at home?
What to do:
1. Pour the milk, cream, vanilla extract and sugar into the small resealable bag.
2. Gently squeeze out any excess air and seal the small bag tightly.
3. Fill half of the large bag with ice. Add the salt into the large bag.
4. Place the sealed small bag on top of the ice. Fill up the large bag with more ice, and seal it tightly.
Now be ready to shake the large bag for 10 minutes! You may wish to wrap a towel around the bag in case it gets too cold.
Once the 10 minutes are done, take the small bag out of the large bag and rinse it with cold water to get rid of any excess salt.
Open up the small bag to enjoy your ice cream!
While shaking the bags, salt may get into your ice cream mix if you do not seal the small bag properly or use strong bags. To prevent this from happening, you may wish to double bag the mix before shaking – once you seal the small bag with your ice cream ingredients, you can place it into a second small bag and seal it.
If you are disappointed by your first batch, don’t worry! You can adjust the ingredients to suit your taste. You can try other flavours, and change the proportions to find the right texture for you.
The next time you buy from the ice cream cart uncle, ask yourself: does your ice cream taste icy or creamy? Is the texture smooth or rough with ice crystals?
But you better not spend too long thinking – or your ice cream will melt first!
Don’t feel like having ice cream but want to make another cool treat? You can make fruit slushies by following the steps in the video below:
Written by Goh Wanling
Illustrated by Lee Ai Cing