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Properties of 2D shapes introduces students to key vocabulary used to describe the uniqe properties of 2D and 3D shapes. This is a prerequisite unit before moving on to drawing 3D shapes in Term 2 of Year 9. Learning progresses from describing 2D shapes to performing basic transformations such as rotations, enlargements, translations and reflections.

**Prerequisite Knowledge**

- distinguish between regular and irregular polygons based on reasoning about equal sides and angles.
- know angles are measured in degrees: estimate and compare acute, obtuse and reflex angles
- draw 2-D shapes using given dimensions and angles

**Success Criteria**

- use conventional terms and notations: points, lines, vertices, edges, planes, parallel lines, perpendicular lines, right angles, polygons, regular polygons and polygons with reflection and/or rotation symmetries; use the standard conventions for labelling and referring to the sides and angles of triangles; draw diagrams from written description
- derive and apply the properties and definitions of: special types of quadrilaterals, including square, rectangle, parallelogram, trapezium, kite and rhombus; and triangles and other plane figures using appropriate language
- identify and apply circle definitions and properties, including: centre, radius, chord, diameter, circumference, tangent, arc, sector and segment

**Key Concepts**

- Understanding and using the vocabulary is key throughout this topic.
- Regular polygons are closed shapes with straight lines of equal length.
- Students need to recognise different types of quadrilaterals and triangles by their geometrical properties.
- All shapes have a rotational symmetry of at least one.
- Reflected vertices are an equal distance from the line of symmetry.

**Common Misconceptions**

- Students often confuse the part of a circle.
- Diagonal lines do not have to be slanted and can be horizontal or vertical.
- A circle is not a polygon since its edge of not straight.
- Rectangles are incorrectly assumed to have a rotational symmetry of order 4.

January 1, 2021

Problem solving lesson on two-way tables and frequency trees.

December 20, 2020

Three typical exam questions to revise on plotting quadratic, cubic and reciprocal graphs.

December 2, 2020

Linking cumulative frequency graphs to ratio, percentages and financial mathematics.