Rectangles, rhombuses and squares
- Measure the two crossings — 3 tasks
- What a rectangle inherits — 3 tasks
- The rectangle’s diagonals — 3 tasks
- The rhombus’s diagonals — 3 tasks
- Going Deeper — 6 tasks
- Practice — 24 tasks
- Summary — 2 tasks
- Both criteria, and the one that adds nothing — 3 tasks
Classroom activities
Things a class does rather than writes on. Each one is a finished PDF: print it, cut it up if it says so, and hand it round.
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What Does One More Mark Add? Rectangles and Rhombuses — Cut & Glue Sort 25 minutes, including the cutting · 5 sheets
12 parallelograms, each with one more mark (a right angle, equal diagonals, equal sides next to each other, perpendicular diagonals, a halved corner, and more), sorted into "makes it a rectangle", "makes it a rhombus" and "adds nothing". The last row holds marks that are true of every parallelogram, drawn to look like rectangles and rhombuses on purpose.
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Rectangle Rule or Rhombus Rule? — Answer Maze 10–15 minutes · 4 sheets
8 boxes on one page about rectangles and rhombuses: angles and lengths at the crossing of the diagonals, whether a diagonal cuts a corner in half, and which figure a parallelogram must be. Every wrong answer is the other figure's fact leaking in: equal diagonals in a rhombus, perpendicular diagonals in a rectangle. The row of box numbers at the foot is the check.
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Do the Marks Make a Rhombus? — Mystery Picture 25–35 minutes · 4 sheets
25 squares, each a shape drawn to look like a rhombus or a square, with ticks, arrowheads, arcs, right-angle marks or diagonals: fill the square only if the marks prove it is a rhombus. Squares whose marks prove them count, because a square is a rhombus. Perpendicular diagonals on their own, four right angles, and marks every parallelogram has stay white. When every square is right, a picture appears.
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Rectangles, Rhombuses and Squares — Scavenger Hunt a full class period · 13 sheets
16 cards around the room, each asking an angle or a length inside a rectangle or a rhombus drawn with both diagonals. The common mistakes are the other shape's facts: equal diagonals in a rhombus, four equal angles at the crossing of a rectangle, the wrong corner halved. Each lands on a card that sends the group back, and a clean run is 8 lines on the record sheet.