Take three hands-up answers, not open call-outs. Give a few seconds of quiet think-time first.

You only need the shapes visible on the board for this question. Don't reveal the sorting rules yet — this hook is just to get pupils noticing that we can pick one feature to group by.

Walk each shape aloud, one at a time, and name the property you are checking before you reveal it.

• Square — stress that it fits two rules: '4 corners' and 'all sides equal'. This is the seed of the two-groups idea later.
• Rectangle — fits '4 corners' but NOT 'all sides equal'.
• Triangle and circle — use these to show what gets left out of a 'four corners' rule. With the circle, name explicitly that its edge is one smooth curve and it has no straight sides — this grounds the 'has corners' idea pupils sort by later.

Say the property each time, e.g. 'our rule is four corners — does this shape pass?'

If the board is unavailable: sketch each shape on the whiteboard, or hold up the matching paper card, and count the sides and corners by pointing to each one with your finger as the class counts aloud.

This round is for talking it through together — a pupil reveals the property on the board, the whole class calls pass or fail, then the class names which group the shape belongs to. There are no group boxes in the tool, so the grouping happens out loud against the fixed rule.

Use the inspector only to reveal the side or corner count so the class can see it before deciding. Say the sorting rule aloud before each shape, and keep it fixed for the whole round.

Pacing: between rules, do a quick turn-and-name ("name me one shape that passed our last rule") and revoice a pupil's answer each time, so the watching rows stay with you across the round.

Watch for pupils sorting by how a shape looks rather than by the named property — a tilted square is still a square. Revoice: 'we check the rule, not the tilt.'

If the board is unavailable: sketch each shape on the whiteboard, or hold up the matching paper card, and count its sides and corners by pointing as the class counts aloud, then ask the class which group it belongs to.

This round is the hands-on practice. Hand out one set of printed shape cards per group so every pupil has the real shapes in front of them, and sort at the desks — this is not a board demonstration.

Give the rules one at a time, not all four at once. Say a rule, let groups sort, check together, then reveal the next rule. Each rule narrows the set: the last rule should leave only the square.

• Rule 1 (has corners) — the circle is the only one left out; the triangle, square, rectangle and hexagon all stay in.
• Rule 2 (exactly four sides) — the triangle and the hexagon drop out here, since the hexagon has more than four sides.
• Rules 3 and 4 — this is where the rectangle drops out but the square stays. Draw out that the square passes both parts.

Ask pupils to say each rule aloud before they start, then keep to it.

Note on the hexagon: the hexagon is used here informally as a 'count the sides' shape — pupils count that it has six sides and so fails the 'exactly four sides' rule. It is named and taught more fully in a later lesson; here it is just a useful extra shape to count.

Keep this brisk — recap the three bullets and point ahead to triangles and quadrilaterals.