Foundations of Mathematical Thinking · Junior Infants

Active learning ideas

Classifying Polygons

Active learning works for classifying polygons because students need to manipulate shapes to truly see their properties. When children handle sticks, straws, or cutouts, they connect abstract side counts to concrete examples, building lasting understanding.

• NCCA Curriculum Specifications
• NCCA: Junior Cycle - Strand 3: Geometry and Trigonometry - G.1.5

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

Activity 01

• Stations Rotation
• 30 min · Small Groups

Shape Sorting Bins: Polygon Classification

Prepare bins labeled by side number: 3, 4, 5, 6. Provide cut-out shapes, both regular and irregular. Students sort shapes into bins, then check with a partner by counting sides aloud. Discuss any mismatches as a group.

Differentiate between regular and irregular polygons.

Facilitation Tip

During Shape Sorting Bins, label each bin with a side count and model sorting 2-3 shapes before letting students work independently.

What to look for

Provide students with a collection of shape cutouts including polygons and non-polygons (like circles, ovals). Ask them to sort the shapes into two groups: 'Polygons' and 'Not Polygons'. Observe which students correctly identify polygons and can articulate why a circle is not one.

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

Activity 02

• Stations Rotation
• 25 min · Pairs

Stick and Straw Builds: Regular vs Irregular

Give students pipe cleaners or straws and playdough. Instruct them to build a triangle, first regular by making equal sides, then irregular. Pairs compare and describe differences in side lengths.

Explain why a circle is not considered a polygon.

Facilitation Tip

For Stick and Straw Builds, demonstrate how to align sides evenly when constructing regular polygons to avoid crooked edges.

What to look for

Give each student a card with a drawing of a polygon. Ask them to write the number of sides on the card. Then, ask them to draw one example of a regular polygon and one example of an irregular polygon on the back of the card.

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

Activity 03

• Stations Rotation
• 20 min · Whole Class

Classroom Shape Hunt: Polygon Spotting

Students walk the room to find polygons on objects like books or tiles. They draw or photograph finds, noting side count and regular or irregular nature. Share in a whole-class tally chart.

Construct a polygon with a specific number of sides and identify its properties.

Facilitation Tip

When leading the Classroom Shape Hunt, assign small groups to photograph polygons and label their side counts before sharing with the class.

What to look for

Hold up a square and a rhombus that is not a square. Ask students: 'Are both of these quadrilaterals? How can you tell if a quadrilateral is regular or irregular?' Guide them to discuss equal sides and angles.

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

Activity 04

• Stations Rotation
• 35 min · Individual

Polygon Printing: Side Count Art

Use foam shapes or cookie cutters dipped in paint. Children print polygons on paper, count sides for each print, and label regular or irregular. Individual reflection follows with a side-count checklist.

Differentiate between regular and irregular polygons.

Facilitation Tip

During Polygon Printing, remind students to count sides carefully before pressing the shape into the ink pad to avoid smudged prints.

What to look for

Provide students with a collection of shape cutouts including polygons and non-polygons (like circles, ovals). Ask them to sort the shapes into two groups: 'Polygons' and 'Not Polygons'. Observe which students correctly identify polygons and can articulate why a circle is not one.

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

A few notes on teaching this unit

Teachers approach this topic by starting with hands-on exploration before introducing formal terms. Use everyday objects first, then connect them to geometric names. Avoid rushing to definitions; let students discover properties through building and sorting. Research shows that tactile engagement with polygons strengthens spatial reasoning, so prioritize activities where students physically handle shapes rather than just observe them.

Successful learning looks like students confidently sorting shapes by side count, distinguishing regular from irregular polygons, and explaining their reasoning. They should use precise vocabulary and connect geometric terms to real-world objects with ease.

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Watch Out for These Misconceptions

• During Shape Sorting Bins, watch for students who place circles with polygons. Redirect by asking them to trace the circle's edge with a finger to feel the absence of straight sides.

  Ask students to compare a circle cutout to a triangle model, then trace both edges to highlight the difference between curved and straight lines.

• During Stick and Straw Builds, watch for students who insist all four-sided shapes are squares. Redirect by having them build a rectangle with unequal sides to see the variety of quadrilaterals.

  Ask students to construct a square first, then modify one side to create a rectangle, discussing why it remains a quadrilateral but is no longer regular.

• During Classroom Shape Hunt, watch for students who overlook pentagons or hexagons. Redirect by focusing their hunt on objects with five or six sides, like soccer balls or tiles.

  Provide a checklist with odd and even side counts to guide their search, ensuring they encounter polygons with varying side numbers.

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Methods used in this brief

• Stations Rotation