Grade 3/Geometry
Perimeter of L-Shapes (1108)
Calculate the perimeter of L-shaped polygons.
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Quick Tip
Add the lengths of all outer sides. Don't forget the missing sides!
Teacher Resources
Teaching Notes
This collection focuses on perimeter of l-shapes. Use grid paper to help students visualize area and perimeter.
Vocabulary
Missing side: An edge length not given.
Parallel sides: Sides that are the same distance apart.
Common Mistakes
- Confusing Area and Perimeter formulas
- Forgetting to double the sides for Perimeter
- Using wrong units (e.g., cm instead of sq cm for Area)
- Missing a side length
- Confusing perimeter with area
- Incorrect sum of lengths
- Not identifying all 6 sides
Differentiation
SupportHave students trace shapes on grid paper and count squares.
ChallengeChallenge students to find multiple rectangles with the same area but different perimeters.
Discussion Questions
- What is the difference between Area and Perimeter?
- Can two rectangles have the same perimeter but different areas?
- Why do we use 'square' units for area?
- How do L-shapes differ from rectangles?
- What strategies can help find all side lengths?
- Could an L-shape have different side lengths but the same perimeter?
- How is perimeter useful in real life?
Extension Activities
- Measure the classroom floor area.
- Design a garden with a specific perimeter.
- Create art using only rectangles of specific areas.
Parent Tip
Use string to measure the perimeter of an L-shaped object.
Learning Path
Skill Cluster
Geometry & Measurement
Estimated Time
20 minutes
Skills Practiced
perimeter of l-shapes
Prerequisites
- 1107
- Perimeter of rectangles
- Addition of whole numbers
Next Steps
- Area of L-Shapes
- Perimeter with algebraic expressions
- Perimeter of Irregular Polygons
- Finding Missing Sides: Perimeter