The children at Farm Lane School have a unique custom. Because of the underfloor heating, the floor tiles keep coming unstuck, and when they are repaired, different colours are used. New girl Nisba in Year 3 is soon told that only Year 4s are allowed to walk on the green tiles. Nisba, being tall, can stretch to the green tiles easily, but Lucy and her chums in Year 4 are menacing. Nisba is quite sure of herself and walks on the green tiles anyway, whereupon she is tripped up and hurts her arm. The solution is found when gray tiles are put down one weekend, and Nisba is the only one with legs long enough to walk on them. Teachers who become aware of the problem help too, and the situation is resolved. This short, imaginative story, with large print and excellent black and white illustrations, shows clearly the kind of silly small things that can cause bullying and the sort of self-confidence it takes to cope.