Geometry — 1st Grade Lesson
Students will name common 2D and 3D shapes and describe them by their sides, corners, and faces.
1st Grade · Geometry · ~20 min lesson
2D shapes — flat shapes
2D shapes are flat. Learn them by their sides and corners (also called vertices).
| Shape | Sides | Corners |
|---|---|---|
| triangle | 3 | 3 |
| square | 4 | 4 |
| rectangle | 4 | 4 |
| circle | 0 | 0 |
3D shapes — solid shapes
3D shapes are solid — you can hold them. They have faces, edges, and corners.
| Shape | What it looks like | Real examples |
|---|---|---|
| sphere | round ball | basketball, globe |
| cube | box with equal sides | dice, blocks |
| cone | pointed with a round base | ice cream cone |
| cylinder | like a can | soup can, paper towel roll |
Sides and corners
- A side is a straight edge of a shape.
- A corner is where two sides meet.
Count them carefully: a triangle has 3 of each; a square has 4 of each.
2D vs 3D
- A circle is flat — it’s 2D.
- A sphere is round and solid — it’s 3D.
- A square is flat — it’s 2D.
- A cube is solid — it’s 3D.
Shape hunts
Shapes are everywhere. Look around: a window is a rectangle, a clock is a circle, a can of soup is a cylinder, a basketball is a sphere.
How to practice at home
- Shape hunt: find every 2D and 3D shape in one room.
- Play-dough shapes: roll spheres, cubes, and cones.
- Sort the toys: group blocks by shape.
- Count sides and corners on pictures in books.
Practice with the exercises above, then download these free printable worksheets:
Practice Exercises
Try these on your own, then reveal the answer to check.
How many sides does a triangle have?
💡 Tri means three.
How many corners does a square have?
💡 Each corner is where two sides meet.
Name a shape with 3 sides and 3 corners.
💡 Tri means three.
Is a basketball more like a circle or a sphere?
💡 A sphere is a solid 3D shape you can hold.
How many corners does a rectangle have?
💡 Rectangles have 4 corners like squares.
Which shape has no sides and no corners: a circle or a triangle?
💡 A circle is a smooth round curve.
Printable Worksheets
Put this lesson into practice with free, printable worksheets — each with an answer key.
Before You Start
- Shape names from kindergarten
- Counting to 10
Common Mistakes to Watch For
- Calling a square a rectangle (or the reverse) without checking the sides
- Mixing up a circle and a sphere (flat shape vs solid shape)
What to Learn Next
Browse more Geometry worksheets or explore all 1st Grade worksheets.
Related Worksheets
1st Grade Geometry: 2D Shapes and Their Sides
Name each 2D shape and tell how many sides and corners it has.
3D Shapes Worksheet
3D shapes are solid — you can hold them. Learn cubes, spheres, cones, cylinders, and boxes.
Name the 2D Shapes Worksheet
Look at each shape and write its name — circle, square, triangle, rectangle, or star.
Count Sides and Corners Worksheet
Look at each shape and count its sides or corners.
Types of Angles Worksheet (Acute, Right, Obtuse)
Look at each angle and tell whether it is acute (less than a right angle), right, or obtuse (more than a right angle).
Coordinate Plane: Identify the Coordinates
Write the ordered pair (x, y) for each labeled point on the coordinate grid.
Frequently Asked Questions
What shapes does a 1st grader need to know?
2D shapes — circles, squares, rectangles, and triangles — plus 3D shapes like spheres, cubes, cones, and cylinders. Students describe them by sides, corners, and faces.
What is the difference between a 2D and a 3D shape?
A 2D shape is flat (a drawing of a square). A 3D shape is solid and has depth (a cube you can hold). A circle is flat; a sphere is round like a ball.
Original & reviewed. Every worksheet is created in-house from a grade-level skill brief, checked for a correct answer key, and reviewed for grade-appropriateness. Our editorial policy.