Rotation vs reflection

A candidate is shown an asymmetric F shape and four answer options. Two options are rotations of F (by 90° and 180° clockwise). Two options are reflections. Explain two contrasting checks the candidate should perform to distinguish rotations from reflections, and give an example of each.

Mark scheme (4 marks): Award up to 2 marks per check (1 for the check, 1 for a worked example).

• Check 1 — Chirality / mirror test (2 marks): A reflection produces a mirror image, so an asymmetric letter such as F appears backwards (prongs on the wrong side). A rotation preserves handedness — F's prongs always remain on the original side of the spine. Example: a backwards F whose prongs point left instead of right is a reflection, not a rotation, even if it looks 'turned'.
• Check 2 — Track a single asymmetric feature through the angle (2 marks): Pick the top prong of the F and track where it lands. After 90° clockwise it should sit on the right of the spine; after 180° it should be at the bottom on the original side. If the prong is on the opposite side of the spine, it is a reflection. Example: an F-shape with prongs at the bottom but on the left of the spine is a reflected-then-rotated figure, not a pure rotation.

Accept any equivalent contrasting checks (e.g. shading preservation, edge-length tracking) provided they genuinely distinguish the two transformations.