Rotation rules (around a fixed central point): (1) 90° CLOCKWISE: top → right; right → bottom; bottom → left; left → top; (2) 90° COUNTERCLOCKWISE (or 270° clockwise): top → left; left → bottom; bottom → right; right → top; (3) 180°: top → bottom; right → left; bottom → top; left → right (equivalent to flipping both axes); (4) 270° clockwise (or 90° counterclockwise) — see above; (5) 360°: back to original position. Quick mental method: imagine a clock face. The hour hand at 12 is 'top'; rotating 90° clockwise puts it at 3 (right); another 90° → 6 (bottom); another 90° → 9 (left); back to 12. REFLECTION (mirroring) is different from rotation: (a) MIRROR ACROSS VERTICAL LINE: left and right swap (top stays top, bottom stays bottom); (b) MIRROR ACROSS HORIZONTAL LINE: top and bottom swap (left stays left, right stays right); (c) Mirroring is generally NOT the same as rotation, except for shapes with certain symmetry.
Practical for ao: when a shape is rotated in an answer choice, find a distinctive feature (a specific corner, a unique edge, a point marking) in the original, then find where that feature is in the answer. If a point was 'on the top edge near the right corner' in the original, and the shape is rotated 90° clockwise in the answer, the point should now be 'on the right edge near the bottom corner.'.
Shortcuts: many people work better with PHYSICAL ROTATION — turn your test booklet (or imagine doing so) to see if a rotation matches. Square, equilateral triangle, regular polygon, and circle all look the same in some rotations — be careful with their symmetry. A square rotated 90° looks identical to itself (no anatomical change visible). An equilateral triangle rotated 120° looks identical. For these symmetric shapes, marked points are critical for tracking orientation.