2D and 3D Shapes — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. Which 2D shape has the most sides: pentagon, hexagon, or triangle?
A) triangle
B) pentagon
C) hexagon
D) they all have the same
A hexagon has 6 sides, which is more than a pentagon (5 sides) or a triangle (3 sides), so the hexagon wins.
2. How many faces does a square pyramid have in all?
A) 4
B) 5
C) 6
D) 8
A square pyramid has 1 square face on the bottom plus 4 triangular faces on the sides — that equals 5 faces altogether.
3. Which 3D shape has 2 flat circular faces and 0 vertices?
A) cone
B) sphere
C) cylinder
D) cube
A cylinder is the only shape with two circle faces on its ends joined by a smooth curved side — and because there are no corners, it has 0 vertices.
4. A cereal box is most like which 3D shape?
A) cube
B) rectangular prism
C) cylinder
D) triangular prism
A cereal box has 6 rectangular faces, 12 edges, and 8 corners — all the features that define a rectangular prism.
Part B: Fill in the Blank
Write the correct answer on each line.
1. A hexagon has 3 more sides than a triangle.
A hexagon has 6 sides and a triangle has 3 sides, so 6 − 3 = 3 more sides on the hexagon.
2. A cube and a rectangular prism both have 6 faces.
Both a cube and a rectangular prism are box shapes with a top, bottom, front, back, and two sides — that is 6 faces each.
3. A 2D shape has length and width but no depth.
2D shapes are flat on paper, so they only have length and width — depth is the third dimension that belongs to 3D shapes.
4. A square has 4 equal sides and a rectangle has 2 pairs of equal sides.
A square has all 4 sides the same length, which is what makes it special compared to a rectangle that only has 2 matching pairs.
5. A square pyramid has 5 faces, 8 edges, and 5 vertices.
These numbers match a square pyramid exactly: 1 square + 4 triangles = 5 faces, 4 base edges + 4 side edges = 8 edges, and 4 base corners + 1 top = 5 vertices.