Give five seconds of quiet think-time, then take three hands-up answers. You want pupils to feel the difference between 'around', 'inside' and 'cubes' before any method is named. Don't resolve it yet — that is what Watch and Notice does.

Work each shape live on the board. For the 5 × 3 rectangle, do it twice: add the four sides for perimeter (16 cm), then count rows and columns for area (15 squares). Point at each number as it lands, this is the distance around, this is the space inside, so pupils see two different numbers, not a mistake.

For the 4 × 4 square, perimeter is 16 and area is 16, same number, different idea. This is the trap; ask 'so is 16 the perimeter or the area?' and let the class untangle it.

For the L-shape, draw it as two joined rectangles and find the area only (count inside). Bottom piece: 4 squares by 2 squares, so 4 × 2 = 8. Upright piece on the left: 2 squares by 2 squares, so 2 × 2 = 4. Add the two parts: 8 + 4 = 12 squares inside. Check by counting each unit square once so none is double-counted. Slip to watch: pupils who multiply the outer length by the outer width as if the L were a full rectangle.

For the cube stack, count the bottom layer of 4, then the top layer of 4, and stress that we count the 8 cubes even though some are hidden. Keep it to cues, do not read a script.

Talk this one through together — pupils take turns at the board and the class agrees or corrects out loud.

Drag the corners on the board to make each shape in turn (start from the 6 × 2 rectangle already set), and switch to 3D for the cube stack. Ask the pupil at the board to name the method first ('around', 'inside' or 'cubes'), then work it. For the 3 × 3 square, do both perimeter and area so the class hears that one shape can answer two questions. For the cube stack, count the bottom layer, then the top, and add the hidden cubes. Watch for pupils who add sides when the question wants squares, or count squares when it wants the distance around — that mix-up is the whole point of the lesson.

This is the practice round — 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.

Before each problem, ask the class to name the method: tape is perimeter, slabs are area, 'more space' is area, packing cubes is volume. The trap is the sign border (3 + 2 + 3 + 2 = 10 m, not 6 m from multiplying). For the two mats, pupils compute both on screen (2 × 5 = 10 squares, 3 × 3 = 9 squares) and see that the 2 by 5 mat covers more. For the box, count 4 cubes in each of the 2 layers (4 × 2 = 8). Let pupils predict which method each job needs before they compute.