For staff: the Monday drop, two minutes to set up.

Before the children arrive. Pin the printed "old photo" somewhere low on a wall among other papers, for the youngest to find by its bell shape. Put the printed museum card at the front desk or by the door. Draw four empty branches on the case board.

The sealed printable. Print two things: the photo of a bell with a thin crack, labelled 1998, and the card "Club bell, cast in 1912. Cracked, 1998. To be mended."

The episode. Read the story aloud, or play the recording. About five minutes.

Jobs by age. The youngest find the photo by matching the bell's shape. The middle group reads the card and works out how old the bell is. The oldest label the four branches and decide which ones the evidence snaps off.

The answer. The bell is cracked, because two sources agree. "Taken to be mended" stays in pencil: one source is not two.

No printer? Draw the bell with a crack line and write the card by hand.

The Elders' Clue (for home). Write this on the back of the printable: How can you tell a cracked bell, or a cracked cup, from a whole one without looking at it? Only a grown-up can answer it. Next Monday, pin their answers to the case board in pencil, under "what grown-ups remember". Nothing has to come back; the room carries on either way.

For the ride home. Ask: what is something you checked twice this week, and how?