Changes Around Us: Physical and Chemical: common misconceptions

If your child says… “It looks the same, so nothing changed.”

Ask together

What does touching the bottle tell you that looking misses?

What’s true

Sight alone cannot reveal every change.

If your child says… “If I cannot undo it, it must be chemical.”

Ask together

Did tearing make another substance, or smaller pieces of paper?

What’s true

A physical change need not be reversible.

If your child says… “Nothing new can form without heating.”

Ask together

Does the diagram show heating before the new white solid forms?

What’s true

Chemical reactions can happen at room temperature.

If your child says… “Rust is just dirt.”

Ask together

Where could rust on this clean nail have come from?

What’s true

Rust contains iron that came from the object.

If your child says… “The cover makes all the wax run out.”

Ask together

What fuel remains after the flame goes out?

What’s true

The flame goes out when too little oxygen remains to keep it burning.

If your child says… “Everything happening beside a flame must be chemical.”

Ask together

Does melted wax become another substance just because a flame is nearby?

What’s true

Each part of a process needs judging separately.

If your child says… “Weathering and erosion mean the same thing.”

Ask together

Did our tray show rock breaking down, or soil moving elsewhere?

What’s true

Breaking down rock and carrying material away are different changes.

If your child says… “If burning fuel is useful, it cannot cause harm.”

Ask together

Where does the carbon dioxide go after the cooking is finished?

What’s true

A wanted change can also have harmful effects over time.