If one explanation fits an observation, every other explanation must be impossible.

Zara hears a bump and thinks her cat knocked something over. What should she do before deciding?

• Think of another cause.
• Decide it was the cat.
• Ignore any other clues.

A door shuts. Your first idea is that someone pushed it. Which is a different possible explanation?

• A breeze pushed the door.
• A person pushed the door.
• A person shoved the door.

A torch will not light. Jo considers a loose bulb or a flat battery. Which plan checks both explanations?

• Replace the battery and assume the bulb fits.
• Ask an adult to check the bulb and battery.
• Tighten the bulb and assume the battery works.

Leo wonders whether his drooping plant has too little water or too much water. Which check could help tell these ideas apart?

• Count the leaves.
• Ask an adult whether the soil is dry or soggy.
• Choose the first idea without checking any clues.

Thinking of a new explanation does not prove that the new explanation is true.

Two friends hear a crash from another room. They consider a fallen jar or a slammed door, but have no other clues. What can they conclude?

• It was the jar because they named that idea first.
• It was the door because they named that idea last.
• They need more clues to choose between the ideas.

Mia's toy car will not move. She considers dead batteries or a stuck wheel. She finds string holding a wheel still. Which explanation does that clue support?

• The wheel is stuck.
• Flat batteries.
• Both causes are proved.