# Stage 2 - space and geometry

## Strategy

Students can:

• Identify various 2D shapes
• Mark lines of symmetry in a variety of 2D shapes
• Classify angles

## Activities to support the strategy

### Teaching strategy – examples and non-examples

Identification of shapes requires conceptual understanding. This is best taught by providing a definition of the concept along with examples and non-examples of the concept. Likewise conceptual understanding of symmetry is best taught by providing a definition followed by examples and non-examples of the concept.

When using the principles of ‘examples and non-examples’ to teach conceptual understanding start with non-examples that are very different from the target shape or concept then gradually include non-examples that differ only slightly from the target shape.

These questions require conceptual understanding that could be taught using examples and non-examples.

### Examples of teaching concepts by example and non-example

• Concept of a circle
• Definition – a circle is a flat round shape with every point on its edge being the same distance from the middle. • View/print (PDF 328.84KB)
• Include circles of various sizes, colours and texture.
• Model language while sorting
• Include shape work across KLAs and across the school day.

Use the same approach to teach the concept of a cylinder and prism by providing a definition and then showing examples and non-examples of the concept.

• Concept of a right angle
• Definition – a right angle is an internal angle which is equal to 90 degrees. Note: The special symbol like a box in the angle. If you see this, it is a right angle. The 90° is rarely written in. If you see the box in the corner, you are being told it is a right angle. This box does not always appear in a right angle.

All the angles below are right angles: A right angle can be in any orientation or rotation as long as the internal angle is 90°.

Make up a range of cards showing examples and non-examples of a right angle.

Have students respond to each card by saying “right angle” or “not a right angle”.

• Remember to start with non-examples that are quite different from a right angle and move to non-examples that are close to a right angle.
• Use the same strategy to teach concepts of acute angle and obtuse angle
• Concept of a line of symmetry View/print (PDF 183.53KB)

• Definition – a line of symmetry divides a shape so that each side of the line is exactly the same.
• Have students determine the lines of symmetry for a range of shapes.
• Have students fold shapes along a line that is NOT a line of symmetry.

## References

#### Australian curriculum reference

ACMMG088: Compare and describe two dimensional shapes that result from combining and splitting common shapes, with and without the use of digital technologies ACMMG066: Identify symmetry in the environment

#### NSW syllabus reference

MA2-15MG: Manipulates, identifies and sketches two-dimensional shapes, including special quadrilaterals, and describes their features. MA2-16MG: Identifies, describes, compares and classifies angles

## Numeracy app

Symmetry Shuffle is a “Math Doodles” recreational math puzzle for the iPad that will sharpen your spatial reasoning and get your neurons sparking. It takes only minutes to learn and months to master, but beware, once you start playing you may never see things the same!