Give five seconds of quiet think-time, then take two or three hands-up answers. Listen for pupils noticing the reflection points the opposite way. Revoice: so the mirror flips it round to face the other side.

Walk each example aloud, one at a time.

• Vertical line — say the triangle flips left to right; it is never just slid over.
• Horizontal line — emphasise the flip is now top-to-bottom, same idea, different line.
• L-shape — point to one corner, count its squares from the line aloud, then count the same on the far side. This equal-distance counting is the heart of the lesson.
• Diagonal line — mark the slant line clearly and say the flip still keeps every corner the same distance, but we count along the slant. This builds the diagonal case before pupils meet it later.

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

Invite an individual pupil to tap cells to build a small shape on one side of the chosen mirror line; the tool auto-mirrors each tap across the line. Before confirming each flip, do a quick turn-and-name: name a pupil to say how many squares one corner sits from the line, then name another to say where its reflection should land. Ask the class to check: is the flipped corner the same number of squares from the line? Rotate three or four pupils, revoicing a clear answer each time. Watch for pupils expecting the shape to slide rather than flip — pause and revoice when the reflection faces the opposite way.

This round is the practice bank — 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.

Narrate the which way does it flip? question each time. The diagonal-line reflection at the end is an optional stretch — lead it explicitly with the class, marking the slant line and checking one corner's distance aloud together, and only run it if time allows. Watch for the slide-not-flip slip on the arrow shape: if the arrow still points the same way, it has been moved, not reflected.