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.

Walk each shape aloud, one at a time, pointing to each side as you say its length.

• Triangle — 3 + 4 + 5 = 12 cm. Touch each side once.
• L-shape — this is the trap shape: all six sides count, including the two short inside steps. 5 + 2 + 3 + 3 + 2 + 5 = 20 cm. Run a finger right around and check nobody loses a side.
• Square — 6 + 6 + 6 + 6 = 24 cm. Ask 'do we have to measure all four?' to plant the equal-sides idea for next lesson.
• Rectangle — 8 + 3 + 8 + 3 = 22 cm.

Say the key phrase verbatim: touch 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.

Call individual pupils up one at a time to click each side of a shape. The rest of the class watches the running total and confirms the final answer. Mix in a four-sided shape and at least one shape with five or six sides so the count every side point keeps getting practised. If a pupil double-clicks a side or skips one, pause and ask the class did the ant walk that edge already?

Two questions to put to the pupil at the board: Which side did you start on, and did you end back there? How many sides did this shape have altogether?

This round is the practice bank — 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.