Types of Quadrilaterals and Their Names for 3rd Grade

Learn the names and characteristics of different quadrilaterals: squares, rectangles, rhombuses, parallelograms, and trapezoids with visual diagrams and step-by-step explanations.

Quadrilateral Names Chart

QUADRILATERAL NAMES & SHAPES

SQUARE
  • 4 equal sides
  • 4 right angles
  • Opposite sides parallel
  • Also called: Special rectangle
RECTANGLE
  • 4 right angles
  • Opposite sides equal
  • Opposite sides parallel
  • Square is special type
RHOMBUS
  • 4 equal sides
  • Opposite sides parallel
  • Opposite angles equal
  • Square is special type
PARALLELOGRAM
  • Opposite sides equal
  • Opposite sides parallel
  • Opposite angles equal
  • Square, rectangle, rhombus are special types
TRAPEZOID
  • At least 1 pair of parallel sides
  • Most general type
  • Others are special types
  • May have equal legs
🎯 Complete Summary of Quadrilateral Names

Names & Definitions:

  • 🔸 Quadrilateral: A polygon with 4 sides, 4 vertices, and 4 angles
  • ### Square: 4 equal sides + 4 right angles + opposite sides parallel
  • ### Rectangle: 4 right angles + opposite sides equal and parallel
  • ### Rhombus: 4 equal sides + opposite sides parallel + opposite angles equal
  • ### Parallelogram: Opposite sides parallel and equal + opposite angles equal
  • ### Trapezoid: At least one pair of parallel sides

Core Rules & Principles:

  • ### Angle Sum Property: All quadrilaterals have interior angles that sum to 360°
  • ### Hierarchy: Square ⊂ Rectangle ⊂ Parallelogram ⊂ Quadrilateral
  • ### Hierarchy: Square ⊂ Rhombus ⊂ Parallelogram ⊂ Quadrilateral
  • ### Parallel Sides: Key attribute for classification beyond trapezoid

Step-by-Step Naming Method:

  • ### Step 1: Count sides (must be 4 for quadrilateral)
  • ### Step 2: Check for parallel sides
  • ### Step 3: Measure or compare side lengths
  • ### Step 4: Check angle measures
  • ### Step 5: Apply specific definitions to name

Multiple Examples (Simple → Advanced):

  • ### Simple: Square tile (4 equal sides, 4 right angles)
  • ### Simple: Rectangle book cover (4 right angles, opposite sides equal)
  • ### Intermediate: Rhombus diamond shape (4 equal sides, no right angles)
  • ### Intermediate: Parallelogram slanted rectangle (opposite sides equal and parallel)
  • ### Advanced: Trapezoid roof shape (one pair of parallel sides)

Tips, Tricks & Common Pitfalls:

  • ### Tip: Draw arrows on parallel sides to help visualize
  • ### Tip: Remember that squares are both rectangles AND rhombuses
  • ### Tip: Use angle sum property (360°) to verify calculations
  • ### Pitfall: Don't confuse trapezoids with parallelograms
  • ### Pitfall: Forgetting that all squares are rectangles
  • ### Pitfall: Assuming all parallelograms have right angles

Key Notes for Memorization:

  • ### Memory Aid: "Squares are Special Rectangles and Rhombuses"
  • ### Memory Aid: "All Quads Have 360° Total"
  • ### Memory Aid: "TRAPezoid has TRAP for parallel sides"
  • ### Memory Aid: "PARAllelogram has PARA of parallel sides"
1 Square name and attributes
Exercise 1
Identify the name and describe all attributes of a square with sides of 5 cm.
Definition:

Square: A quadrilateral with four equal sides and four right angles (90°). It is both a rectangle and a rhombus.

Square
5cm
Name:
  • ✓ Square
  • ✓ Also called: Special rectangle
  • ✓ Also called: Special rhombus
  • ✓ Part of parallelogram family
Sides:
  • ✓ 4 equal sides
  • ✓ Opposite sides parallel
  • ✓ All sides = 5 cm
  • ✓ Perimeter = 20 cm
Angles:
  • ✓ 4 right angles (90°)
  • ✓ All angles equal
  • ✓ Sum of angles = 360°
  • ✓ Adjacent angles supplementary
Step 1: Count the sides

A square has 4 sides, making it a quadrilateral

Step 2: Measure side lengths

All 4 sides are equal (5 cm each)

Step 3: Check angles

All 4 angles are right angles (90° each)

Step 4: Verify parallel sides

Opposite sides are parallel to each other

Name: Square | 4 equal sides, 4 right angles, opposite sides parallel
Final answer:

This shape is called a square because it has 4 equal sides of 5 cm each and 4 right angles.

Applied rules:

• Name: Square is the specific name for this shape

• Parallelism: Opposite sides of a square are always parallel

• Angle sum: All quadrilaterals have interior angles that sum to 360°

More Quadrilateral Names
📐 Quadrilateral = 4-sided polygon
Basic Definition
Square
4 equal sides, 4 right angles
All sides equal, all angles 90°
Rectangle
Opposite sides equal, 4 right angles
Opposite sides equal, all angles 90°
Rhombus
4 equal sides, opposite angles equal
All sides equal, opposite angles equal
2 Rectangle name and attributes
Exercise 2
Identify the name and describe all attributes of a rectangle with length 8 cm and width 4 cm.
Definition:

Rectangle: A quadrilateral with four right angles and opposite sides equal and parallel. All squares are rectangles.

Rectangle
8cm × 4cm
Name:
  • ✓ Rectangle
  • ✓ Also called: Oblong (sometimes)
  • ✓ Square is special type
  • ✓ Part of parallelogram family
Sides:
  • ✓ Opposite sides equal
  • ✓ Opposite sides parallel
  • ✓ Length = 8 cm, Width = 4 cm
  • ✓ Perimeter = 24 cm
Angles:
  • ✓ 4 right angles (90°)
  • ✓ All angles equal
  • ✓ Sum of angles = 360°
  • ✓ Adjacent angles supplementary
Step 1: Count the sides

A rectangle has 4 sides, making it a quadrilateral

Step 2: Measure side lengths

Opposite sides are equal (length = 8 cm, width = 4 cm)

Step 3: Check angles

All 4 angles are right angles (90° each)

Step 4: Verify parallel sides

Opposite sides are parallel to each other

Name: Rectangle | Opposite sides equal, 4 right angles, opposite sides parallel
Final answer:

This shape is called a rectangle because it has 4 right angles and opposite sides that are equal and parallel.

Applied rules:

• Name: Rectangle is the specific name for this shape

• Parallelism: Opposite sides of a rectangle are always parallel

• Special case: A square is a special type of rectangle where all sides are equal

3 Rhombus name and attributes
Exercise 3
Identify the name and describe all attributes of a rhombus with sides of 6 cm.
Definition:

Rhombus: A quadrilateral with four equal sides, opposite sides parallel, and opposite angles equal. All squares are rhombuses.

Rhombus
6cm
Name:
  • ✓ Rhombus
  • ✓ Also called: Diamond (informally)
  • ✓ Square is special type
  • ✓ Part of parallelogram family
Sides:
  • ✓ 4 equal sides
  • ✓ Opposite sides parallel
  • ✓ All sides = 6 cm
  • ✓ Perimeter = 24 cm
Angles:
  • ✓ Opposite angles equal
  • ✓ Adjacent angles supplementary
  • ✓ Sum of angles = 360°
  • ✓ Not necessarily right angles
Step 1: Count the sides

A rhombus has 4 sides, making it a quadrilateral

Step 2: Measure side lengths

All 4 sides are equal (6 cm each)

Step 3: Check parallel sides

Opposite sides are parallel to each other

Step 4: Examine angles

Opposite angles are equal, adjacent angles are supplementary

Name: Rhombus | 4 equal sides, opposite sides parallel, opposite angles equal
Final answer:

This shape is called a rhombus because it has 4 equal sides and opposite sides that are parallel.

Applied rules:

• Name: Rhombus is the specific name for this shape

• Special case: A square is a special type of rhombus where all angles are right angles

• Diagonals: Diagonals of a rhombus bisect each other at right angles

🧠 Memory Aids for Names
  • 💡 Square: "Square = Fair (all sides fair/equal)"
  • 💡 Rectangle: "Rect-angle = Right angles only"
  • 💡 Rhombus: "Rhombus = Diamond shape"
  • 💡 Parallelogram: "Parallel = Same direction, never meet"
  • 💡 Trapezoid: "Trap = One pair caught in parallel trap"
Name Comparison & Quick Reference
4 Parallelogram name and attributes
Exercise 4
Identify the name and describe all attributes of a parallelogram with sides of 7 cm and 5 cm.
Definition:

Parallelogram: A quadrilateral with opposite sides parallel and equal in length. Squares, rectangles, and rhombuses are all parallelograms.

Parallelogram
7cm × 5cm
Name:
  • ✓ Parallelogram
  • ✓ Square, rectangle, rhombus are special types
  • ✓ Part of quadrilateral family
  • ✓ Most general type with parallel sides
Sides:
  • ✓ Opposite sides equal
  • ✓ Opposite sides parallel
  • ✓ Two pairs of equal sides
  • ✓ Perimeter = 24 cm
Angles:
  • ✓ Opposite angles equal
  • ✓ Adjacent angles supplementary
  • ✓ Sum of angles = 360°
  • ✓ No right angles required
Step 1: Count the sides

A parallelogram has 4 sides, making it a quadrilateral

Step 2: Check side lengths

Opposite sides are equal (one pair = 7 cm, other pair = 5 cm)

Step 3: Verify parallelism

Opposite sides are parallel to each other

Step 4: Examine angles

Opposite angles are equal, adjacent angles add up to 180°

Name: Parallelogram | Opposite sides equal and parallel, opposite angles equal
Final answer:

This shape is called a parallelogram because it has opposite sides that are equal and parallel.

Applied rules:

• Name: Parallelogram is the specific name for this shape

• Special case: Squares, rectangles, and rhombuses are all special types of parallelograms

• Angle property: Adjacent angles in a parallelogram are supplementary (add to 180°)

5 Trapezoid name and attributes
Exercise 5
Identify the name and describe all attributes of a trapezoid with one pair of parallel sides.
Definition:

Trapezoid: A quadrilateral with at least one pair of parallel sides. This is the most general category of quadrilateral.

Trapezoid
Parallel sides
Name:
  • ✓ Trapezoid
  • ✓ Also called: Trapezium (UK)
  • ✓ Most general quadrilateral type
  • ✓ Others are special types
Sides:
  • ✓ At least one pair parallel
  • ✓ Usually unequal sides
  • ✓ 4 total sides
  • ✓ Variable perimeter
Angles:
  • ✓ Angles vary
  • ✓ Adjacent angles along parallel sides are supplementary
  • ✓ Sum of angles = 360°
  • ✓ No equal angles required
Step 1: Count the sides

A trapezoid has 4 sides, making it a quadrilateral

Step 2: Identify parallel sides

Look for at least one pair of parallel sides

Step 3: Check other properties

Other sides may or may not be equal, angles vary

Step 4: Confirm definition

Must have exactly one pair of parallel sides

Name: Trapezoid | At least one pair of parallel sides
Final answer:

This shape is called a trapezoid because it has at least one pair of parallel sides.

Applied rules:

• Name: Trapezoid is the specific name for this shape

• Key feature: Only requires one pair of parallel sides (unlike parallelograms)

• Angle property: Adjacent angles along the parallel sides are supplementary

Type Square Rectangle Rhombus Parallelogram Trapezoid
Official Name Square Rectangle Rhombus Parallelogram Trapezoid
Also Called Special rectangle/rhombus Oblong (sometimes) Diamond (informal) None Trapezium (UK)
Number of sides 4 4 4 4 4
Equal sides 4 equal Opposite equal 4 equal Opposite equal Varies
Parallel sides 2 pairs 2 pairs 2 pairs 2 pairs At least 1 pair
Complete Review & Practice
🔷 Quadrilateral Hierarchy
Classification System
Key definitions for 3rd Grade:

Quadrilateral: A polygon with 4 sides and 4 vertices

Parallel lines: Lines that never meet and stay the same distance apart

Right angle: An angle that measures exactly 90 degrees

Equal sides: Sides that have the same length

3rd Grade naming method:
  1. Count sides: Must have exactly 4 sides
  2. Look for parallel sides: Draw arrows to help visualize
  3. Check side lengths: Are they equal or different?
  4. Check angles: Are they right angles (90°)?
  5. Name: Apply the correct name
Tip 1: Remember: "Quad" means four, so quadrilaterals always have 4 sides.
Tip 2: The sum of all interior angles in any quadrilateral is always 360°.
Tip 3: A square is both a rectangle AND a rhombus!
Tip 4: All squares are rectangles, but not all rectangles are squares.
Common errors for 3rd graders: Confusing trapezoids with parallelograms, forgetting that squares are also rectangles and rhombuses.
Memory aid: "All squares are rectangles, but not all rectangles are squares."
Properties to remember:

• Square: 4 equal sides + 4 right angles + diagonals equal + diagonals perpendicular

• Rectangle: 4 right angles + opposite sides equal + diagonals equal

• Rhombus: 4 equal sides + opposite angles equal + diagonals perpendicular

• Parallelogram: Opposite sides parallel and equal + opposite angles equal

• Trapezoid: At least one pair of parallel sides

Questions & Answers

Question: I'm confused about squares and rectangles. Is a square also a rectangle? How can that be?

Answer: Great question! Yes, a square is also a rectangle. Let me explain why:

  • A rectangle is defined as having 4 right angles and opposite sides equal
  • A square has 4 right angles (so it meets the rectangle requirement) AND all sides equal

Think of it like this: A square is a "special" rectangle where not just opposite sides are equal, but ALL sides are equal. It's like saying "all squares are rectangles, but not all rectangles are squares."

Example: A rectangle with sides 4cm × 6cm is not a square. But a rectangle with sides 5cm × 5cm IS a square because it has 4 right angles AND 4 equal sides.

Question: My child is having trouble remembering the names of different quadrilaterals. How can I help them?

Answer: Here are effective strategies for 3rd graders:

  • Visual association: Square = "Fair" (all fair/equal), Rectangle = "Long" shape, Rhombus = Diamond shape
  • Hands-on activities: Use straws or sticks to build different quadrilaterals
  • Real-world examples: TV screen (rectangle), diamond earrings (rhombus), floor tiles (square)
  • Practice with sorting: Have your child categorize different quadrilaterals by name

Create a simple chart with your child showing the key features of each shape. Focus on one attribute at a time: first count sides (must be 4), then check angles, then sides, then parallelism.

Remember: Patience and repetition are key for young learners!

Question: Why do we call them quadrilaterals? That's a big word!

Answer: Great question! The word "quadrilateral" comes from Latin:

  • "Quad" means four
  • "Lateral" means sides

So "quadrilateral" literally means "four sides"! It's just a fancy math word for any shape that has four sides. We have other similar words like "triangle" (tri = three, angle = corner) and "pentagon" (penta = five, gon = angle).

Even though it's a big word, it just tells us the most basic thing about these shapes: they all have four sides!