Fold a shape drawn on paper along a line and hold it up so pupils see the two halves match. Take two or three hands-up predictions about the co-ordinates, then move on. Do not confirm the rule yet.

Y-axis example: write one corner on the board, e.g. (2, 3), and its image (−2, 3). Same height, same distance across, opposite side. Draw out that only the x-co-ordinate flipped sign.

X-axis example: this is the x-axis mirror. Ask which co-ordinate flips this time? before you confirm it is the y-co-ordinate, so the mirror is the x-axis. Watch for pupils who expect both to change — only one flips for an axis reflection.

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

Do the y-axis reflection of the whole triangle first, asking the class to predict each image co-ordinate before the pupil plots it. Then switch to the second prompt: reflect the single corner (3, 2) in the x-axis so pupils see the y-co-ordinate flip while the x stays the same. Reconcile any disagreement by measuring distance from the axis on both sides. Naming the mirror axis each time stops pupils losing track of which co-ordinate flips.

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.

On the final round the label does not name the axis. Ask the class to compare the starting point (6, −4) with its image (−6, −4): the x-co-ordinate flipped and the y stayed, so the mirror must be the y-axis. Have them say the axis aloud before they plot, then let Check confirm it. This is where they practise reading the mirror axis from which co-ordinate changed. Watch for pupils flipping both co-ordinates; head that off by pointing back at Watch and Notice.