# Stage 2 -space and geometry – 2D

Name and describe common 2D shapes; classify quadrilaterals; identify flips, slides and turns

## Strategy

Students can:

• name and describe common 2D shapes
• identify flips, slides and turns

## Activities to support the strategy

### Activity 1 – flip, slide, and turn

Use the following suggested target language to describe the effects of flips, slides and turns.

• If I flip this shape over the dotted line it will look like this.
• If I slide this shape over the dotted line it will look like this.
• If I turn this shape over the dotted line it will look like this.

1. Collect a variety of transparent coloured plastic 2D shapes, such as rectangles, squares, rhombuses, parallelograms, hexagons and trapeziums.

The teacher demonstrates and describes what happens to a shape when it is flipped across a line (flip needs to be demonstrated with a solid shape or a picture on an overhead).

• The teacher repeats to demonstrate what happens to a shape when it is turned and/or when it is slid. #### Guided support

In pairs, students choose a shape and practise flipping, sliding and turning the shape.

Students identify how the shape was moved and draw what happens after the shapes crossed the dotted line.

Example of target language: If the triangle is flipped over the line then it will look like this.

Students hypothesise about what these shapes would look like if they were flipped across a line, then draw what they believe the shape will look like. 2. In pairs, students brainstorm all the places around the school where you might find a flip, slide or turn pattern, e.g. rows of bricks, patterns on a carpet, tiling patterns.

Students look around the school and try to find an example of each type of pattern – a flip, a slide and a turn pattern. They should draw part of the pattern and write where they found it.

### Activity 2 – identifying quadrilaterals

The teacher displays the following shapes on an overhead projector. Ask students to name each shape and identify what these shapes have in common. Write each of the labels on a card. The teacher draws a Venn diagram (reference Mathematics K–6 Syllabus, p.117) to demonstrate that the shapes above are part of a group called quadrilaterals. As the class works through the following definitions the Venn diagram will be completed. The teacher reads the definition of a quadrilateral, i.e. any four-sided figure and asks students to identify which of the five shapes fit that classification. As the students determine that a shape fits this classification, they name it and place it on the diagram in the quadrilateral section.

Note: All five shapes will fit the quadrilateral classification.

• The teacher then reads the definition of a trapezium, i.e. a quadrilateral with at least one pair of opposite sides parallel. As the students determine that a shape fits this classification they name it and place it on the diagram in the trapezium section.

Note: All five shapes will fit the trapezium classification.

• The teacher reads the definition of a parallelogram, i.e. a quadrilateral with opposite sides that are parallel and of equal length and opposite angles that are equal. Place matching shapes on the diagram in the parallelogram section.

Note: All shapes, except the trapezium, fit the parallelogram classification.

• The teacher reads the definition of a rhombus, i.e. a rhombus is a parallelogram with four equal sides and equal opposite angles. Place matching shapes on the diagram in the rhombus section.
• The teacher reads the definition of a square, i.e. a quadrilateral with four equal sides, four right angles and opposite sides that are parallel. Place matching shapes on the diagram in the square section.

Note: A square is a special type of rhombus and a special type of rectangle.

• The teacher reads the definition of a rectangle, i.e. a quadrilateral with four right angles and pairs of equal parallel lines. Place matching shapes on the diagram in the rectangle section.

Teacher supports the students to interpret the diagram and make mathematical statements to classify quadrilaterals, e.g.

• A rectangle is a quadrilateral. It is also a type of trapezium and parallelogram.

Note: For more advanced students the language can include the properties of each of these classifications in the description, e.g.

• A rectangle is a quadrilateral. It may also be considered to be a trapezium that has both pairs of opposites parallel and equal. A rectangle is also a special type of parallelogram that contains a right angle.

Students complete a worksheet in which they have to identify how each shape is classified. Using the completed table students write a short description to classify each of the shapes.

### Activity 3 – identifying other polygons

The students can follow similar activities to explore other polygons using the polygon chart below. These activities can then be repeated using the chart below.   ### Activity 4 - symmetry

1. Students are given a worksheet with a variety of 2D shapes. They cut out each shape and fold it exactly in half in as many ways as they can.

Discuss:

• Which shapes can be folded in half only once?
• Which shapes can be folded in half in more than one way?
• When two halves exactly overlap, what is the line along the fold called?

On each of the cut outs, students draw the line of symmetry along each fold line.

Students complete the table to record whether each of the shapes is symmetrical and indicate how many lines of symmetry each shape has. Students discuss the information. Compare the shapes with the same number of sides. Ask questions such as:

• Do all four-sided shapes have the same number of lines of symmetry?
• Do all five-sided shapes have the same number of lines of symmetry?

2. Students trace around a circular container and cut out the circle. They

• fold the circle in half once
• fold it in half twice
• then fold it again and again and again.

Discuss:

• How many times can you fold a circle exactly in half?
• Can you count the number of times?

Have students explain how many lines of symmetry they think a circle has.

## References

### NSW syllabus

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

## Numeracy App

• Pattern Blocks: Virtual pattern blocks include: triangles, squares, rhombi, trapezoids, hexagons and chevrons