Trace your finger right around the edge of the picture frame (or the IWB frame) and back to the start as you read the question. Take three hands-up answers, not open call-outs. Listen for the idea of measuring the edges and adding them — that is the whole lesson in one sentence.

Point to each side as its length comes up. Triangle: three sides, 3 + 4 + 5 = 12 cm, touch each once.

L-shape is the trap: it bends, so six sides, not four. Run a finger right around so nobody skips the two short inside steps. 5 + 2 + 3 + 3 + 2 + 5 = 20 cm.

Square: all four sides equal, 6 + 6 + 6 + 6 = 24 cm. Ask whether we really need to measure all four, to plant the equal-sides idea for next lesson.

Rectangle: two long, two short, 8 + 3 + 8 + 3 = 22 cm.

Throughout, stress touching each side once and only once.

This round is for talking it through together. Pupils take turns at the board and the class agrees or corrects out loud. No marking yet.

The order matters: the class adds the sides and commits to a total BEFORE anyone reads the P beside the shape. The reading is the check, not the answer. If a pupil reads it first, cover it with a hand and ask for the addition.

The rectangle 5 by 4 is 5 + 4 + 5 + 4 = 18 cm. The square 3 by 3 is 12 cm. The right triangle with legs 4 and 3 has a sloping third side of 5, so 4 + 3 + 5 = 12 cm; the tool gives the sloping side, pupils do not have to work it out.

Drag a corner to resize a shape between turns so the same shape gives a new perimeter. Adding a fifth or sixth side is not possible here, the palette offers rectangles, triangles and circles, so keep the count-every-side point on the three shapes and the copybook step that follows.

These are the practice questions — set the objects out at four or five stations, with two or three copies of each object per station so a small group can each measure and pass on. Keep the pass-on rhythm brisk; the class confirms each reading aloud at the end. If you have fewer copies, run it as a pass-on chain rather than stations so no object sits idle.

Circulate and catch alignment slips on the spot — the ruler's zero must line up with the start of each edge. The triangle is the key check: its three sides must all be added, not just the two that look obvious. For the desktop stretch, remind pupils a desk is measured in centimetres but may run past 30 cm, so they lay the ruler end-over-end. Reconcile any disagreement on a measurement as you circulate.

Recap the key phrase one last time: add every side, touch each side once. The next lesson builds the equal-sides shortcut, so flag the square and rectangle from today as the bridge.