The case in three lines. The Green Gazette calls Station Road the Green's most dangerous crossing: six near-misses this year, against two at School Lane, and a petition now asks for the crossing patrol to be moved. The council's count shows about three thousand people a day cross Station Road and about two hundred cross School Lane, so person for person School Lane has five times the near-misses. With numbers this small, any one year could mislead, and Tara has to write the corrections box.

One question to ask. "What should the box say?" Then: "Should Mrs Adeyemi stay where she is?" Let them argue both sides.

One thing to do at the table. Think of a claim that one place has "the most" of something: the most accidents, the most crime, the most complaints. Ask: the most out of how many? Then guess how many people had the chance, and divide.

The grown-up layer. The case is about rates and counts: a count means little until you know how many had the chance, and busy places have more of everything. It also warns about small numbers, which wobble from year to year. It gives the young reporter his strongest point, that every near-miss he printed happened. It gives the petition organiser hers: the busy road really is frightening. The habits it models are going to the original count, dividing by how many had the chance, and saying how sure the numbers can make you.

The case leaves the line blank on purpose. Ask for it before you offer yours.