Give five seconds of quiet think-time, then take two or three hands-up answers. Don't settle the question yet, the model step proves it.

Point to each part as it appears and name it once, clearly. On the radius, hold out for the class to spot that every radius is exactly the same length, wherever it points.

On the diameter, the key move: it goes through the centre, and it is two radii long. Point out the two radii sitting end to end, one on each side of the centre, before you say the diameter is twice as long as one radius. Say radii aloud and remind the class it just means more than one radius. No circumference and no measuring today.

Pupils take turns coming up to the board; the rest of the class judges each move aloud and corrects it if it is wrong.

Watch for the common slip: a line drawn edge-to-edge that misses the centre is not a diameter. Ask each time: does your line go through the middle dot? When a second radius is set, get the class to judge by eye that it matches the first in length.

This is the practice round with real objects at pupils' desks, shared and passed around; the class confirms the finished drawings aloud at the end. Keep the pass-on rhythm brisk.

The make-or-break is the centre: if the centre dot is off, the diameter won't cross it. Circulate and catch that on the spot, and remind pupils where the centre sat when you folded the scrap circle earlier if their dot is guessy. Revoice a strong answer: your diameter goes through the middle, so it splits the circle into two matching halves.