Take two or three hands-up answers, not open call-outs. Listen for the idea that every point on the compass circle is the same distance from the centre. Revoice: so the compass keeps the exact same gap the whole way round.

• Radius 5 cm — point to the centre first. Then trace the radius out to the edge. Then trace the diameter across, stopping at the centre to show it is one radius plus another radius. Ask what the diameter reads before revealing.
• Radius 3 cm — hold out for the pattern: the diameter shrank with the radius and stayed exactly double. Revoice: the diameter always follows the radius, doubled.
• Chord and arc — name the chord and the arc; head off the common slip that any line across a circle is a diameter (only one through the centre is).

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

For the 6 cm and 2 cm circles, pupils set the radius and predict the diameter (12 cm, then 4 cm) before the read-out confirms it. For the last one, flip it: the diameter is 8 cm, so what radius must the compass be opened to? (4 cm). This is the halving direction pupils find harder.

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.

The radius challenges (3 cm, 7 cm) are the easy to start entry. The diameter challenges (10 cm → radius 5 cm; 6 cm → radius 3 cm) are the stretch — pupils must halve the diameter to find the compass setting. Ask what did you open the compass to? each time.