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Subject: Mathematics
Semester: 2
Period: 6
Week: 32
School Name:
Teacher’s Name:
Subject: Mathematics
Grade Level: Grade 4
Date: Week 32
Lesson Duration: 45 minutes
Week & Period: Week 32, Period 6
Topic: Polygons
Sub-topic: Triangles, Quadrilaterals, and Other Polygons
Learning Objectives
By the end of the lesson, students should be able to:
- Define polygons.
- Identify and classify different types of triangles and quadrilaterals.
- Recognize polygons with more than four sides.
Previous Knowledge
Students already know how to count the sides of simple shapes.
Instructional Materials
Mathematics textbook for Grade 4, cardboard shapes, sticks, straws, chalkboard.
Lesson Development – ABC Model
A – Anticipation (Warm-up / Starter)
Time: 5–10 minutes
Teacher shows cutouts of shapes and asks students to count the number of sides.
B – Building Knowledge (Main Lesson Body)
Time: 25–30 minutes
🧠 Key Definition
🔹 What is a Polygon?
A polygon is a closed, flat (2D) shape made up of straight sides (no curves).
Each polygon has:
- Sides (straight lines)
- Vertices (corners where sides meet)
- Angles (formed between two sides)
✅ Important:
- All polygons are closed shapes (the sides connect back to the start)
- Polygons have at least 3 sides
- Shapes like circles or open figures are NOT polygons
🔺 Triangles (3-sided polygons)
|
Triangle Type |
Description |
Example / Real Life |
|
Equilateral |
3 equal sides and 3 equal angles (each 60°) |
Traffic warning sign |
|
Isosceles |
2 sides equal; 2 angles equal |
Roof gable, triangle pizza slice |
|
Scalene |
No sides or angles are equal |
Uneven tent or sail shape |
|
Right-angled |
One angle is exactly 90° |
L-shaped ramp, triangle ruler corner |
📝 Note: A triangle can be both right-angled and isosceles or scalene.
⬛ Quadrilaterals (4-sided polygons)
|
Quadrilateral Type |
Description |
Example / Real Life |
|
Square |
4 equal sides and 4 right angles (90°) |
Floor tiles, chessboard square |
|
Rectangle |
Opposite sides equal and 4 right angles |
Door, book cover |
|
Parallelogram |
Opposite sides equal and parallel, but angles are not 90° |
Slanted window, leaning picture |
|
Rhombus |
4 equal sides, but angles are not 90° |
Kite, diamond on playing cards |
|
Trapezium (US: Trapezoid) |
Only one pair of parallel sides |
Bridge support, ramp signboard |
📝 Note: All squares are rectangles, but not all rectangles are squares.
🔷 Other Polygons (More than 4 sides)
|
Polygon Name |
Number of Sides |
Example / Real Life |
|
Pentagon |
5 |
The Pentagon building (USA) |
|
Hexagon |
6 |
Honeycomb cell, nuts and bolts head |
|
Heptagon |
7 |
Rare shapes in art or design |
|
Octagon |
8 |
STOP sign (common in road signs) |
🧍♀️ Learners’ Activities (Expanded)
- Hands-on Polygon Building
- Use matchsticks, straws, or toothpicks and clay to build:
- Triangles (all types)
- Quadrilaterals
- Other polygons (e.g., pentagon, hexagon)
- Encourage labeling of:
- Sides
- Angles
- Names of shapes
- Sorting Polygon Cards
- Give each group a set of polygon cards (printed or drawn)
- Task:
- Group the cards as triangles, quadrilaterals, and others
- Further classify into types (e.g., equilateral, square, rhombus)
- Discuss features (sides, angles, parallel lines)
- Polygon Scavenger Hunt (Classroom or Home)
- Learners identify real-life polygon shapes in the classroom:
- Rectangular whiteboard
- Square floor tile
- Triangular wall décor
- Octagonal wall clock
- "Guess My Polygon" Game
- Teacher describes a shape:
“I have 4 sides, 2 long and 2 short, and 4 right angles. What am I?”
➤ Rectangle
✅ Assessment Checks (Oral & Written)
🔸 Oral Questions
- “What is the difference between a square and a rectangle?”
➤ Square has all sides equal, rectangle has opposite sides equal - “How many sides does a hexagon have?”
➤ 6 sides - “Is a circle a polygon?”
➤ No, it has no straight sides - “Can a shape with 3 sides be a polygon?”
➤ Yes, it’s called a triangle
🔸 Written / Exit Ticket
- Draw and label:
- One equilateral triangle
- One trapezium
- One pentagon
- Classify the following:
- Triangle with one 90° angle ➤ Right-angled triangle
- Shape with 4 equal sides, no right angles ➤ Rhombus
- Shape with 8 sides ➤ Octagon
- True or False
- A square is a type of rectangle. ➤ True
- A trapezium has two pairs of parallel sides. ➤ False
🧑🏫 Teacher Notes (Expanded & Detailed)
✏️ Key Teaching Points:
- Use clear diagrams to show differences between similar shapes (e.g., square vs. rhombus).
- Stress number of sides and types of angles as the basis for classification.
- Use math vocabulary repeatedly:
- Vertices, sides, parallel, angles, equal, closed figure
🧩 Common Misconceptions to Address:
- "All four-sided shapes are rectangles" – ❌ Explain different types of quadrilaterals.
- "All triangles are equal" – ❌ Show varied triangle types visually.
📘 Optional Homework / Extension Activity
Polygon Poster Project
- Students create a poster showing:
- 1 example of each triangle
- 1 example of each quadrilateral
- 2 polygons with more than 4 sides
- Real-life object examples for each
Polygon Puzzle Sheet
- Match polygons to their properties:
- “Has 4 equal sides, no right angles” ➤ Rhombus
- “Has 5 sides” ➤ Pentagon
- “Has only one pair of parallel sides” ➤ Trapezium
C – Consolidation (Conclusion & Assessment)
Time: 5–10 minutes
Summary: Polygons are closed figures with straight sides. Triangles and quadrilaterals are special groups, while polygons can also have more sides such as pentagons and hexagons.
Evaluation Method (Expanded)
Exit slip/quiz: Write the name of a polygon with 6 sides.
Assignment (Expanded)
Draw 4 types of triangles and 3 types of quadrilaterals.
Follow-up Activity
Students search their environment for real-life polygons such as windows, tiles, and traffic signs.
Differentiation / Inclusive Strategies
Provide cardboard models for tactile learners. Use pictures for visual learners.
Teacher’s Reflection (After Class)
What worked well? ___________________________________________
What needs improvement? ____________________________________
Students’ engagement level: ☑ High ☑ Medium ☑ Low