ASVAB CampMental Rotation flashcards
8 cards with the formulas, rules and traps from this lesson. Answer in your head, then flip to check.
Rule · 1/8
Quarter-turns: where does the top of a shape go?
Clockwise (12 toward 3): top goes to the right. Counterclockwise (12 toward 9): top goes to the left. 90° CCW equals 270° CW, and a half-turn is the same in either direction.
Formula · 2/8
Five-by-five grid turned about (3, 3): quarter-turn rules for cell (r, c)
Clockwise: . Counterclockwise: . Rows count from the top, columns from the left; (1, 4) turns clockwise to (4, 5).
Formula · 3/8
Five-by-five grid: half-turn rule for cell (r, c)
. Cell (1, 4) goes to (5, 2), the center (3, 3) stays put, and doing it twice returns every cell home.
Formula · 4/8
Math-graph rotations about the origin for point (x, y)
90° CCW: . 90° CW: . 180°: . Example: (3, 1) goes to (−1, 3), (1, −3) and (−3, −1).
Common trap · 5/8
Why not use on a grid with rows counted from the top?
Row numbers grow downward while y grows upward, so the sense of the turn reverses: that rule gives a clockwise picture. Use the row-column rules and test a corner cell.
Term · 6/8
What is handedness (chirality), and what does a rotation do to it?
Whether a shape is a left- or right-handed arrangement, like your two hands. Rotations never change it; a flip reverses it. Spinning b gives q (half-turn); b and d are mirror images.
Strategy · 7/8
Three-pass method for choosing a rotated shape
1) Count: same squares, arm lengths and connections. 2) Direction: turn an imaginary arrow and drop wrong facings. 3) Handedness: check a side-specific feature to drop the mirror copy.
Common trap · 8/8
A choice turns the outline correctly but the dot stays put on the page. Valid?
No. A marker is welded to its cell and turns with the shape, staying in the same part of it (for example the end of the short arm). Check outline and marker together.