Take three hands-up answers, one per job. Give five seconds of quiet think-time before any hands go up.

Steer the class toward the three words without confirming yet: fencing means the distance around the edge, carpet means the flat space inside, packing means the solid space filled. Leave the naming to the next step.

Perimeter rectangle (6 by 3): distance all the way round. Trace a finger round the edge back to the start. 6 + 3 + 6 + 3 = 18 cm, measured in centimetres.

Area rectangle (5 by 4): flat space inside, squares in rows. Before the answer, hands up to predict the square count, take two. Point one full row of five, then count four rows: 5 x 4 = 20 cm squared. The raised two means we count squares, not distance.

Pentagon (side 4): turn-and-name, ask a pupil what regular means now it is on screen, revoice it. All five sides equal, so add in equal groups: five fours = 20 cm, not five different numbers.

Volume box (3 by 2 by 2): solid space in cubes. Trace one bottom layer, 3 along and 2 across = 6 cubes. Now stack the second layer: 6 + 6 = 12 cubes. Count one layer then stack it, the move they use in the challenge.

Name the units contrast: perimeter cm, area cm squared, volume cubes. 18 and 20 look alike but the measures and units differ.

This round is for talking it through together. Pupils take turns at the board and the class agrees or corrects out loud.

The order builds a real point: the same 7 cm by 3 cm rectangle gives perimeter twenty centimetres, then area twenty-one square centimetres — almost the same number, completely different measure and unit. Pause on this pair so the class sees the numbers are close by chance, not because the measures are the same.

For the 4 by 4 square (perimeter sixteen centimetres, area sixteen square centimetres) the numbers really do match — a good why is that? moment, but do not let anyone conclude perimeter and area are ever the same thing. Rotate three or four pupils to the board.

These are the practice questions. Pupils take turns at the board, check each answer, and the class confirms before moving on. Keep the board work brisk rather than over-explaining.

The build here is deliberate. The two garden-bed problems (perimeter twenty metres, then area twenty-one square metres) sit next to each other so pupils meet the same numbers giving two different measures. Then the box moves from one layer (twelve cubes) to the whole solid (twenty-four cubes) — the pause: we count the layer, then stack the layers. Finish on the hall floor, where the skirting (perimeter) and tiles (area) give the same both-measures contrast.

If time: ask which is bigger for the hall — the skirting distance around or the tile area inside, and why.

Watch for the classic slip: a pupil multiplying when the fencing or skirting question wants adding around the edge. Head it off by asking is this around the edge, or the space inside? before they choose the operation.