Reversible Changes: Melting and Freezing

Free sample questions, a clear explanation, and 5 practice skills with an AI tutor that guides without giving the answer away.

Super Science: The Magic of Melting and Freezing!

Hey, Super Scientist! Have you ever built a big, round snowman on a cold day, and then watched it turn into a little puddle when the warm sun came out? That’s not magic, it's science! You just saw something melt.

And guess what? If the night gets super chilly again, that water puddle can turn back into slippery ice. That’s called freezing! Melting and freezing are amazing changes that can go back and forth.

Science Power-Up!

Melting is when a solid turns into a liquid because of heat. (Think: Ice cube → Water)

Freezing is when a liquid turns into a solid because it gets very cold. (Think: Water → Ice cube)

More Than Just Water!

Water isn't the only thing that can do this cool trick! Lots of other things can melt and freeze, too. Have you ever seen:

Butter turning into a golden puddle on warm toast?
Chocolate chips getting all gooey and melty in a hot cookie?
A cheese slice on a hamburger becoming soft and runny?

A Chef's Chocolate Secret!

Let’s think about a chef making yummy chocolate hearts for a cake. How do they do it? With melting and freezing!

First, the chef takes hard, solid chocolate bars and gently heats them. The chocolate melts into a smooth, runny liquid. Then, they pour the liquid chocolate into heart-shaped molds.

Finally, they put the molds in a cool place. The chocolate gets cold and freezes back into a solid shape. Ta-da! Perfect chocolate hearts! By melting and freezing, the chef can change the chocolate's shape to make delicious treats.

Sample questions

1. When an ice cube turns into water because it got warm, what is this change called?

○ Freezing

✓ Melting

○ Boiling

○ Breaking

Answer: Melting — Think about what happens when ice gets warm and turns into a puddle.

2. When something melts, it changes from a solid to what?

○ Gas

○ Air

✓ Liquid

○ Powder

Answer: Liquid — Think about what water looks like after an ice cube melts.

3. What usually makes a solid object start to melt?

○ Making it colder

○ Shaking it

○ Putting it in the dark

✓ Heating it up

Answer: Heating it up — What do you do to make chocolate chips turn into runny chocolate sauce?

Skills in this topic

Define melting as a change from solid to liquid caused by heating.
Define freezing as a change from liquid to solid caused by cooling.
Observe and record the melting of ice and the freezing of water.
Identify other common substances that can melt and freeze (e.g., butter, chocolate).
Explain how a chef can change chocolate from a solid to a liquid and back again to make different treats.

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