Angles in triangles (age 6+)

MathematicsGeometryAges 6–7

Distinguish defining attributes of shapes (e.g. triangles are closed and three-sided) from non-defining attributes (e.g. colour, orientation, overall size)

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Teaching Table

Set out your lesson

Classify triangles by being closed, straight-sided and three-sided, ignoring orientation, colour and size.

Activity

Follow an outline with a finger and distinguish straight from curved lines.

Policy

Directed source edges are preserved, not assumed completed. If the readiness probe is difficult, model with support and record supported practice instead of independent evidence.

Materials

Use the supplied stage-specific structured materials. Plain paper and pencil; screen viewing is optional.

Order

Show, guided, put teaching sheet aside, then task sheets in order; adult keys remain private.

Access

No printing or cutting is required unless explicitly choosing a physical construction. Exact paper alternatives are in each material; adaptations change the evidence mode as stated.

Materials are ready in each step. Use them on screen or print just the current step. Put teaching examples aside before the learner tries.

What this lesson covers and its limits

These are bounded opportunities, not learner attainment. Partial and blocked source requirements remain so.

partial: Distinguish defining attributes of shapes (e.g. triangles are closed and three-sided) from non-defining attributes (e.g. colour, orientation, overall size)
Source title 'Angles in triangles' retained unchanged; actual source contract is defining attributes. No angle-sum or degree-measure claim. This is a bounded task opportunity, not established attainment or automatic use across contexts.
partial: Build and draw shapes that possess defining attributes
Mapped task(s) offer this clause only within the supplied examples. Source title 'Angles in triangles' retained unchanged; actual source contract is defining attributes. No angle-sum or degree-measure claim. No attainment or automatic/general performance is claimed.
partial: Identify that a shape remains a triangle regardless of its size, colour, or orientation
Mapped task(s) offer this clause only within the supplied examples. Source title 'Angles in triangles' retained unchanged; actual source contract is defining attributes. No angle-sum or degree-measure claim. No attainment or automatic/general performance is claimed.
partial: Explain why a given shape is or is not a particular type based on its defining properties
Mapped task(s) offer this clause only within the supplied examples. Source title 'Angles in triangles' retained unchanged; actual source contract is defining attributes. No angle-sum or degree-measure claim. No attainment or automatic/general performance is claimed.
partial: Does {{name}} understand that what makes a shape a triangle is having 3 sides and 3 corners — not its colour or which way it's pointing?
Source title 'Angles in triangles' retained unchanged; actual source contract is defining attributes. No angle-sum or degree-measure claim. This is a bounded task opportunity, not established attainment or automatic use across contexts.

Source title 'Angles in triangles' retained unchanged; actual source contract is defining attributes. No angle-sum or degree-measure claim.

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Classify triangles by being closed, straight-sided and three-sided, ignoring orientation, colour and size.

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Check understanding

Build and draw shapes that possess defining attributes
Identify that a shape remains a triangle regardless of its size, colour, or orientation
Explain why a given shape is or is not a particular type based on its defining properties

“Does your child understand that what makes a shape a triangle is having 3 sides and 3 corners — not its colour or which way it's pointing?”

Curriculum record

Type: Conceptual
Subject: Mathematics
Domain: Geometry
Age range: Ages 6–7

Standards

ccss-math:1.G.1