Classifying Quadrilaterals — Answer Key
Part A: Fix the Sentence
Each sentence has an error. Rewrite it correctly on the line.
1. Fix the sentence:
A rhombus must always have right angles.
Corrected: A rhombus has 4 equal sides but does not need right angles.
Grade 4 students learn a rhombus needs 4 equal sides; only when it also has right angles is it a square.
2. Fix the sentence:
A parallelogram has 4 right angles always.
Corrected: A parallelogram has 2 pairs of parallel sides, with no required right angles.
Grade 4 work on CCSS 4.G.2 stresses parallelograms only need parallel sides; right angles make them rectangles.
3. Fix the sentence:
A trapezoid has 4 equal sides.
Corrected: A trapezoid has exactly one pair of parallel sides; sides may differ.
Grade 4 learners know trapezoids are defined by parallel sides, not by equal side lengths.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. A square has 4 right angles.
Grade 4 students count 4 right angles in a square, one at each corner.
2. A parallelogram has 2 pairs of parallel sides.
Grade 4 work shows parallelograms have 2 pairs of parallel sides.
3. A rhombus has 4 equal sides.
Grade 4 students remember a rhombus has 4 equal sides, like a tilted diamond.
4. A trapezoid has exactly 1 pair of parallel sides.
Grade 4 lessons define a trapezoid by its single pair of parallel sides.
Part C: Short Answer
Answer each question in one or two complete sentences.
1. Name two ways a rectangle and a rhombus are different.
Sample answer: A rectangle has 4 right angles, but a rhombus does not need them. A rhombus has 4 equal sides, but a rectangle only needs opposite sides to be equal.
Grade 4 students compare quadrilaterals by listing angle and side properties.
2. Why is a parallelogram not always a rectangle?
Sample answer: A parallelogram only needs 2 pairs of parallel sides. A rectangle also needs 4 right angles. A slanted parallelogram has parallel sides but no right angles, so it is not a rectangle.
Grade 4 students use the right-angle rule to decide when a parallelogram becomes a rectangle.