Lay out (or display) a red-blue-red-blue strip of six pattern blocks as pupils settle. Take three hands-up answers, not open call-outs. Don't confirm the answer yet — the method to be certain is what Watch and Notice will build. Give five seconds of quiet think-time before any hands go up.

Two-shape unit (triangle, square repeating): ring the first triangle-square pair with your finger. This repeating part is the unit, two shapes long. Ask for the eighth shape and how the unit helped; every second shape is a square.

Three-shape unit (triangle, triangle, square repeating): unit is three shapes long. Ask where the squares keep landing. They land on the third, sixth and ninth shapes. This is the key point the lesson rests on, so hold here until the class can say every third shape is a square.

Skipping ahead: count along the row in threes, three, six, nine, landing on a square each time. Make the point that we needn't lay out nine blocks. Counting in threes is faster, and the unit length is the times-table we count in to skip ahead.

This round is for talking it through together — pupils take turns at the board and the class agrees or corrects out loud.

Start a unit on the pattern-blocks board (e.g. circle, square, triangle), then call an individual pupil up to add two more full repeats and ring the unit. Have the class agree the next shape before the pupil places it. Rotate four pupils across units of length two and three. Watch for the common slip of ringing too many or too few shapes as the unit, that is the moment to revoice where does the pattern start to repeat?

These are the practice questions — 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.

For each target, ask the class first: how does knowing the unit length help us skip ahead? For the twentieth shape of a three-shape unit, model counting in threes on the board (three, six, nine, twelve, fifteen, eighteen) and then stepping the last two on, so pupils see they don't need to lay out twenty shapes. The on-screen Check confirms each one — use the ✓ as part of your narration (yes, that's it).