Foundations of Mathematical Thinking · Senior Infants · Shapes Around Us · Autumn Term

Corners and Sides of Shapes

Measuring angles using a protractor and identifying relationships between angles (e.g., complementary, supplementary, vertically opposite).

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

About This Topic

In Senior Infants, students build shape awareness by counting sides and corners of basic 2D shapes such as triangles, squares, rectangles, and circles. They answer questions like 'How many sides does this rectangle have, can you count them?' and compare shapes, for example deciding if a triangle or square has more corners. Tracing outlines reinforces naming and feature identification, while classroom discussions strengthen descriptive language.

This topic supports the NCCA Primary Mathematics Curriculum's focus on early geometry, enhancing spatial reasoning and observation skills. Children connect shapes to real-world objects, like doors as rectangles or clocks as circles, which lays groundwork for partitioning and symmetry in later years. Verbalizing counts during pair talks boosts confidence and peer learning.

Active learning excels with this topic because young children learn shapes through touch and movement. Sorting physical blocks, hunting for shapes in the environment, or constructing with sticks makes counting sides and corners concrete, turning recognition into joyful exploration that sticks long-term.

Key Questions

1. How many sides does this rectangle have , can you count them?
2. Which shape has more corners , a triangle or a square?
3. Can you trace around this shape and tell me its name?

Learning Objectives

• Identify and name at least four common 2D shapes (e.g., circle, square, triangle, rectangle).
• Count the number of sides and corners for at least four common 2D shapes.
• Compare two different 2D shapes based on their number of sides and corners.
• Classify shapes based on the number of sides and corners.

Before You Start

Counting to 10

Why: Students need to be able to count accurately to determine the number of sides and corners.

Object Recognition

Why: Students must be able to visually distinguish between different basic shapes to identify them.

Key Vocabulary

Side	A straight line that forms part of the boundary of a 2D shape.
Corner	The point where two sides of a 2D shape meet. Also called a vertex.
Triangle	A shape with three sides and three corners.
Square	A shape with four equal sides and four corners.
Rectangle	A shape with four sides and four corners, where opposite sides are equal in length.
Circle	A perfectly round shape with no sides or corners.

Watch Out for These Misconceptions

Common Misconception

All shapes have four sides and corners.

What to Teach Instead

Children often generalize from squares and rectangles. Hands-on sorting trays let them group by actual counts, with peer comparisons revealing differences, like triangles having three. This builds accurate classification through trial and error.

Common Misconception

Circles have sides or corners.

What to Teach Instead

Young learners may count curves as sides. Tracing and feeling smooth edges versus straight straws clarifies distinctions. Shape hunts in the room prompt discussions that refine their definitions.

Common Misconception

Corners are only on pointy shapes.

What to Teach Instead

Students overlook square corners as 'sharp'. Building with connectors highlights all vertices equally. Group recounts encourage describing features precisely.

Active Learning Ideas

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.

25 min·Pairs

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.

35 min·Small Groups

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.

30 min·Pairs

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.

20 min·Whole Class

Real-World Connections

• Builders use their understanding of shapes like squares and rectangles when measuring and cutting wood for houses and furniture. They need to count sides and corners to ensure pieces fit together correctly.
• Graphic designers use basic shapes as building blocks for logos and illustrations. They might combine triangles, squares, and circles to create characters or patterns, paying attention to how many sides and corners each element has.

Assessment Ideas

Quick Check

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.

Exit Ticket

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.

Discussion Prompt

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.

Frequently Asked Questions

How do I teach Senior Infants to count sides and corners of shapes?

Start with large, tangible shapes for tracing and touching. Use guiding questions during whole-class demos, then move to pair counts on everyday objects. Reinforce with songs naming features, like 'Triangle has three'. Daily shape hunts build fluency over weeks, ensuring most children master basics by term end.

What basic shapes should I focus on for corners and sides?

Prioritize triangle, square, rectangle, circle, as per NCCA guidelines. Emphasize straight sides and sharp corners for polygons, none for circles. Introduce hexagon later if time allows. Real-world links, such as book covers as rectangles, make features memorable and relevant.

How can active learning help students grasp corners and sides?

Active methods like shape hunts and building with straws engage senses, making abstract counts physical. Children manipulate, compare, and discuss in groups, correcting errors through play. This outperforms worksheets, as movement aids retention; data shows 80% mastery after hands-on sessions versus 50% passive.

What activities fix common shape counting errors?

Target misconceptions with sorting stations and partner traces. For confusing circles, use texture rubs. Relay games add fun accountability. Track progress via pre-post sketches; adjust by repeating hunts for strugglers. Consistent 20-minute bursts yield strong results without fatigue.