For the Qualifications and Curriculum Authority's unit 3D, in which pupils are required to make a picture frame, I show the class a rectangle of card and tell them that a piece of wood is needed to border one edge to begin the frame. I present four options: a large, wide piece of wood; a long piece that's the right width; a piece that's the right length, but too wide; and a piece that's too short. The children have to choose one and justify their reasoning.
Here are some other scenarios, with the QCA units in brackets: lplaygrounds (1B) - children select the best object for the beam of a see-saw. They can choose from a lolly stick, a piece of card, a thick plank of wood, some fabric and a Lego beam.
lvehicles (2A) - choose from Blu-Tak, tape, glue or a piece of plastic tubing to stop a wheel slipping off an axle.
lstorybooks (4B) - select paper, thin card, medium card or thick card to make a pop-up mechanism.
Responses can be written in a chart with three columns: task, best material, and why.
Andy Seed, primary supply teacher and PGCE tutor in primary Damp;T, Leeds University Damp;TSubject Focus, pages 32-37