Reversible and Irreversible Changes for Kids: Can You Undo It? (Grade 2 Science)

Hi, I'm Luna from DoodleBeez. When we heat or cool things, they change. But can we always change them back again? Today we will sort changes into ones we can undo and ones we cannot.

Some changes can be undone. These are called reversible changes. Freeze water and it becomes ice. Warm the ice and it melts back into water. It is still water the whole time.

Chocolate melts when it gets warm, and it turns solid again when it cools. Crayon wax does the same. Melting and freezing are reversible, because we can switch back and forth.

Other changes cannot be undone. These are called irreversible changes. When you cook an egg, it turns from runny to firm. You can never turn a cooked egg back into a raw egg!

Baking a cake, toasting bread and burning wood are irreversible too. Heat changes them into something new. You cannot turn toast back into soft bread, or ashes back into a log.

Here is a helpful clue. If heating or cooling only changes the state, like solid to liquid, it is usually reversible. If it makes a brand new material, like toast or ash, it is usually irreversible.

Now it's your turn. A snowman melts into a puddle on a sunny day. Can this change be undone? Pause and try. Yes, it is reversible! If the puddle freezes, it turns back into solid ice.

Great job! Remember, reversible changes like melting and freezing can be undone. Irreversible changes like cooking, baking and burning make something new and cannot be undone. Practice changes in the Science Lab at doodlebeez.com. See you next time!