Foundations of Mathematical Thinking · Senior Infants

Active learning ideas

Corners and Sides of Shapes

Active learning helps young children grasp sides and corners because they need to see, touch, and manipulate shapes to truly understand their features. Counting sides on a real shape or building one with straws makes abstract ideas concrete, which builds confidence and accuracy in early math skills.

• NCCA Curriculum Specifications
• NCCA: Junior Cycle - Geometry and Trigonometry - GT.2

• 20–35 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Experiential Learning
• 25 min · Pairs

Shape Hunt: Classroom Quest

Provide clipboards and shape checklists. Students walk the room in pairs, find objects matching target shapes, count sides and corners, and sketch one example per shape. Pairs share one find with the class at the end.

How many sides does this rectangle have , can you count them?

Facilitation Tip

During Shape Hunt: Classroom Quest, give each pair a clipboard with a checklist so students can mark off shapes once counted and verified by a partner.

What to look for

Provide students with cut-out shapes (e.g., a square, a triangle, a circle). Ask them to point to a side and count how many sides the shape has. Then, ask them to point to a corner and count the corners. Record their ability to correctly identify and count for each shape.

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Activity 02

• Experiential Learning
• 35 min · Small Groups

Sorting Station: Sides Challenge

Set up trays with mixed shape cutouts. In small groups, children sort by number of sides or corners into labelled baskets, then recount to verify. Discuss why a square fits in the 'four sides' group.

Which shape has more corners , a triangle or a square?

Facilitation Tip

At the Sorting Station: Sides Challenge, provide trays labeled with numbers 3, 4, 5, and 6 to help students self-correct as they place shapes.

What to look for

Give each student a worksheet with drawings of two different shapes, for example, a square and a triangle. Ask them to draw a circle around the shape with more corners and write the number of sides for each shape next to it.

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Activity 03

• Experiential Learning
• 30 min · Pairs

Build and Count: Straw Shapes

Give pipe cleaners or straws and playdough. Students follow picture cards to build a triangle, square, and rectangle, count sides and corners aloud, then compare their models with a partner.

Can you trace around this shape and tell me its name?

Facilitation Tip

During Build and Count: Straw Shapes, model how to pinch straws at corners to create clear vertices before students begin.

What to look for

Hold up two different shapes, like a rectangle and a square. Ask: 'Which of these shapes has more corners? How do you know?' Encourage students to count the corners aloud and explain their reasoning to a partner before sharing with the class.

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Activity 04

• Experiential Learning
• 20 min · Whole Class

Trace Relay: Shape Race

Draw large shapes on paper at stations. In teams, one child traces a shape, counts features, tags the next. Whole class tallies results on a shared chart.

How many sides does this rectangle have , can you count them?

Facilitation Tip

In Trace Relay: Shape Race, assign each runner a different colored marker so you can track individual progress around the room.

What to look for

Provide students with cut-out shapes (e.g., a square, a triangle, a circle). Ask them to point to a side and count how many sides the shape has. Then, ask them to point to a corner and count the corners. Record their ability to correctly identify and count for each shape.

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

A few notes on teaching this unit

Teach this topic by letting students explore before labeling. Allow them to handle real objects, trace outlines, and build shapes before introducing formal terms like ‘corner’ or ‘side.’ Avoid rushing to definitions; instead, ask guiding questions so they discover features through their own actions. Research shows that early exposure to varied shapes reduces overgeneralization and strengthens spatial reasoning.

By the end of these activities, students will name common 2D shapes correctly, count sides and corners independently, and compare shapes using precise vocabulary. They will explain differences between shapes by pointing to and counting features without prompting.

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Watch Out for These Misconceptions

• During Sorting Station: Sides Challenge, watch for students who group all four-sided shapes together without noticing rectangles and squares differ in corner features.

  Ask students to point to each corner on their shapes and count aloud together, emphasizing that corners can be the same size even in different shapes.

• During Shape Hunt: Classroom Quest, watch for students who describe circles as having many sides or corners because of their curves.

  Have students trace the circle with their fingers and compare it to straight straw edges, asking them to feel the difference between smooth and rigid lines.

• During Build and Count: Straw Shapes, watch for students who only count corners on pointy shapes like triangles, missing the corners on rectangles.

  Prompt students to pinch each corner of their straw shape and count all of them, then compare counts with a partner to confirm accuracy.

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Methods used in this brief

• Experiential Learning