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150 multiple-choice questions, 40 flashcards and 10 scenario simulations, written to the Common Core State Standards blueprint. Every question carries a full rationale.
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Common Core State Standards (CCSS) — Mathematics, Grade 3: Geometry (3.G.A.1-2). Public standards from corestandards.org.
CoStudy's 3rd Math: Geometry bank holds 200 items. Every multiple-choice question carries a written rationale explaining why the correct answer is correct and why each distractor is tempting but wrong, and the bank includes 10 scenario-based simulations.
A sample of 12 multiple-choice questions from the bank, with the full rationale shown.
Which has curved edges?
Answer: D — Circle
D) Correct. B/C/A) straight sides.
Is every rectangle a square?
Answer: D — No
D) Correct — rectangles may have unequal sides. B/C) wrong. A) wrong.
A candy bar divided into 4 equal parts. Kim eats 3. Fraction remaining?
Answer: B — 1/4
B) Correct — 1 of 4 left. A) eaten. C/D) reversed/whole.
A rhombus has:
Answer: A — 4 equal sides
Rhombus = 4 equal-length sides. (B) is rectangle; (C),(D) wrong.
To find 1/4 of a shape, split it into how many equal parts?
Answer: D — 4
D) Correct — denominator = # of parts. B) that's for 1/2. C) 1/8. A) whole.
A pyramid with a square base has how many triangle faces?
Answer: A — 4
A) Correct — one per side of square. B/C/D) wrong.
A polygon is a:
Answer: A — Closed figure with straight sides
Polygon = closed + straight sides. (B),(C),(D) wrong.
A rectangle divided into 3 equal parts. Each is:
Answer: C — 1/3
C) Correct. B) count. A) different. D) whole.
A whole is 6 equal parts. Each part is what fraction?
Answer: C — 1/6
C) Correct. B) count. A) 2/6. D) whole.
A square is split into 2 equal triangles by one diagonal. Each triangle is:
Answer: C — 1/2 of the square
C) Correct. B) 4 parts. C/D) wrong.
Are all rhombuses also squares?
Answer: C — No
C) Correct — rhombuses may not have right angles. B/C/D) wrong.
To divide a circle into 4 equal sectors, use:
Answer: B — 2 diameter lines crossing at center
B) Correct — perpendicular diameters. A) 2 pieces. C) not equal. D) not equal.
5 sample cards from the 40 in the bank.
What is an 'acute angle'?
An angle smaller than a right angle (less than 90°).
True or false: All rectangles are squares.
False. Most rectangles have unequal long and short sides — only the special ones with all equal sides are squares.
If a circle is split into 4 equal slices and 3 are eaten, what fraction is left?
1/4.
What is a quadrilateral?
Any 4-sided closed shape.
What is a 'regular polygon'?
A polygon where ALL sides and ALL angles are equal. Like a square, equilateral triangle, regular hexagon.
These samples are a small slice. The full bank runs flashcards, multiple choice and timed mock exams with per-chapter progress tracking, on the web and in the iOS app.
The 3rd Math: Geometry bank holds 200 items: 150 multiple-choice questions, 40 flashcards and 10 scenario-based simulations. 17 of them are on this page to read free, with no signup.
Yes. Every multiple-choice item carries a written rationale that states the controlling principle behind the correct answer and then addresses each wrong option in turn — why it tempts and precisely where it fails. Knowing why the plausible answer was wrong is worth more than knowing which letter was right.
Common Core State Standards (CCSS) — Mathematics, Grade 3: Geometry (3.G.A.1-2). Public standards from corestandards.org.
The samples on this page are free to read in full, rationales included, with no account. The complete 200-item bank, the timed mock exams and per-chapter progress tracking are part of CoStudy on the web and in the iOS app.
Last reviewed 2026-08-22. Banks are written against the certifying body's published exam outline and re-checked when that outline changes — exams get renumbered, retired and reweighted, and a bank written to a superseded outline teaches the wrong proportions. Figures that are re-indexed annually are deliberately not asserted as rules; the questions test the governing principle instead.