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Properties Of 2D Shapes A polygon is a many sided shape with straight sides. To be a regular polygon all the sides and angles must be the same. Add images to this table.

Shape

Number of sides

Number of corners

other

Square

4

4

Rectangle

4

4

Triangle

3

3

Circle

?

0

Oval

?

0

Pentagon

5

5

Hexagon

6

6

Octagon

8

8

Parallelogram

4

4

Kite

4

4

Rhombus

4

4

Trapezium

4

4

4 sides of equal length and 4 right angles 2 pairs of equal sides and 4 right angles Triangles ALWAYS have 3 sides. The interior angles of a triangle add up to 180 degrees A 2-dimensional shape made by drawing a curve that is always the same distance from a center any curve that looks like an egg or an ellipse If all angles are equal and all sides are equal, then it is regular, otherwise it is irregular If all angles are equal and all sides are equal, then it is regular, otherwise it is irregular If all angles are equal and all sides are equal, then it is regular, otherwise it is irregular opposite sides are the same length and are parallel (pushed over rectangle) A kite has got two pairs of sides next to each other that have equal length. But none of the sides are parallel 4 sides of equal length and opposite sides are parallel and angles are equal (pushed over square) 4 sides of which one pair are parallel sides

Compiled by Skills for Life & Work – March 2011


2D Shapes

Angles Compiled by Skills for Life & Work – March 2011


What is an angle? An angle is formed if 2 lines have a common endpoint. Here are some examples

Types of Angles. What is a right angle?

An angle with 90 degrees (90°)

What is an angle less than 90 degrees called?

Acute.

What is an angle more than 90 and less than 180 degrees called? Obtuse. 180 degrees is a straight line. Over 180 and less than 360 degrees is called a reflex angle. Identify the following (2 of each):

Right Angles If an angle looks like an L then it is called a right angle.

Compiled by Skills for Life & Work – March 2011


Can you write your name and count how many right angles there are?

Activity! Give 3 examples of names. Students identify how many right angles.

Compiled by Skills for Life & Work – March 2011


Triangles All the interior angles in a triangle add up to 180 degrees. There are 3 types of triangle; 1. Equilateral – all sides and interior angles the same. 2. Isosceles – 2 sides and 2 interior angles the same. 3. Scalene – all sides and interior angles are different. Could you draw them? State which type each of the following triangle is (6 – 2 of each)

Shapes With Parallel Lines Parallel lines are lines which always stay the same distance apart. For example, train lines. What shapes have parallel lines and can you draw them? Which shapes have parallel lines (images from page 1)?

What is symmetry? Symmetry of shape describes how, under certain rules of movement, a shape can fit exactly onto itself. We are going to look at line symmetry A shape can be folded along a line so that one half of the shape fits exactly onto the other half. (Or you can put a mirror there and see the original shape).

Use a pencil to draw as many lines of symmetry as you can for each shape Compiled by Skills for Life & Work – March 2011


Multi choice – how many lines of symmetry are in the following:

Feedback to include diagrams Tessellations A tessellation is a pattern of shapes that are put together and fit nicely around each other. Also there are no gaps between any of the shapes. For example

A tessellation could be made out of two shapes. So, for example, octagons and squares could make a tessellation.

Compiled by Skills for Life & Work – March 2011


But if you just had octagons, there would be no tessellation as there would be square shaped gaps! Where in real life do you see tessellations? Try and draw some below!

Discussion forum: Here are two examples – a wall and a patio.

Can you give any more examples?

Compiled by Skills for Life & Work – March 2011

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