Mathematics · Class 3

Active learning ideas

Sides and Vertices of 2D Shapes

Active learning helps students grasp sides and vertices by moving beyond static images. When children touch, build, and sort shapes, they connect abstract definitions to concrete experiences. This hands-on approach builds memory and confidence for recalling properties later.

• CBSE Learning Outcomes
• NCERT Class 3, Chapter 5: Shapes and Designs - Counting edges and corners.
• CBSE Syllabus Class 3: Geometry - Describes 2D shapes by the number of sides and corners (vertices).
• NEP 2020: Foundational Numeracy - Analyzes properties of simple shapes.

• 25–45 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Inside-Outside Circle
• 30 min · Pairs

Shape Hunt: Classroom Objects

Pairs search the classroom for objects matching given shapes, count sides and vertices, and sketch them in notebooks. Groups present one find each, justifying counts with classmates. Conclude with a class chart of examples.

Explain the key characteristic that distinguishes a side from a vertex.

Facilitation Tip

For Shape Hunt, provide a checklist with images of shapes so students match objects to shapes before counting.

What to look for

Show students flashcards with different 2D shapes (triangle, square, rectangle, pentagon, hexagon, circle). Ask them to hold up fingers to indicate the number of sides and then the number of vertices for each shape. Observe for accuracy and speed.

• Remember
• Understand
• Apply
• Relationship Skills
• Self-Management

Activity 02

• Inside-Outside Circle
• 45 min · Small Groups

Straw Builders: Custom Shapes

Small groups cut straws to specified lengths and connect with tape to form shapes with exact sides and vertices, like a 5-sided shape. Test stability, then label parts. Display and compare creations.

Construct examples of shapes with a specific number of sides and vertices.

Facilitation Tip

During Straw Builders, demonstrate how to join straws at vertices using small balls of clay for stability.

What to look for

Provide each student with a worksheet. On one side, they must draw a shape with 5 sides and 5 vertices and label them. On the other side, they must write one sentence explaining why a circle is different from a square.

• Remember
• Understand
• Apply
• Relationship Skills
• Self-Management

Activity 03

• Inside-Outside Circle
• 40 min · Small Groups

Attribute Sorting Stations

Set up stations with cutouts: sort by number of sides, then vertices. Rotate groups every 10 minutes, record sorts, and discuss patterns. End with a whole-class shape family tree.

Justify why a circle has no sides or vertices.

Facilitation Tip

In Attribute Sorting Stations, rotate student groups every 6 minutes to keep energy high and avoid fatigue.

What to look for

Ask students to look around the classroom and identify three objects that are examples of 2D shapes. For each object, have them state the shape and then count its sides and vertices. Encourage them to explain their reasoning for identifying the number of sides and vertices.

• Remember
• Understand
• Apply
• Relationship Skills
• Self-Management

Activity 04

• Inside-Outside Circle
• 25 min · Whole Class

Vertex Tracing Relay

Whole class lines up; first student traces a shape's vertices on board, names count, tags next. Repeat for sides. Time teams for speed and accuracy.

Explain the key characteristic that distinguishes a side from a vertex.

What to look for

Show students flashcards with different 2D shapes (triangle, square, rectangle, pentagon, hexagon, circle). Ask them to hold up fingers to indicate the number of sides and then the number of vertices for each shape. Observe for accuracy and speed.

• Remember
• Understand
• Apply
• Relationship Skills
• Self-Management

A few notes on teaching this unit

Begin with real-world examples like floor tiles or book covers to anchor learning. Avoid starting with definitions; instead, let students discover properties through guided exploration. Research shows children learn geometric terms best when they first experience the concept physically before naming it.

By the end, students will confidently count sides and vertices in any 2D shape. They will explain why a circle differs from polygons and justify their counts using tools like rulers or straws. Clear articulation during discussions shows true understanding.

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Watch Out for These Misconceptions

• During Shape Hunt, watch for students who count curved edges as sides in classroom objects like clocks or plates.

  Prompt them to trace the object's outline with their finger and ask, 'Is this edge straight or curved?' Use a ruler to demonstrate how sides must be straight to count.

• During Straw Builders, watch for students who assume all four-sided shapes have equal sides or vertices.

  Have them build a rectangle and a parallelogram side by side, then count vertices together. Ask, 'Do both shapes have 4 sides and 4 vertices? Why does the shape look different?'

• During Attribute Sorting Stations, watch for students who group circles with polygons because both are 'closed shapes'.

  Ask them to draw a circle freehand and then a square using a ruler. Compare the 'corners' and explain, 'Circles have no corners, so they have zero vertices.' Let peers verify by counting aloud.

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Methods used in this brief

• Inside-Outside Circle