2D Shapes Vocabulary
Let’s see how many words we
use to describe or are
connected with 2D shapes
2D shapes - words
2D or 2 dimensional
tessellation (to tessellate)
length
Symmetrical (symmetry)
width
regular polygon
side
composite (complex) shape
angle
diameter
right-angle
radius
parallel
circumference
In pairs, talk about the words and decide on a definition to share with the group
Tessellation – is covering an area
with shapes leaving no spaces
You can use
the same
shape.
Tessellation – is covering an area
with shapes leaving no spaces
You can use
the same
shape.
Return
Symmetry is when both sides of the shape
or pattern are the same when viewed from
the central line.
Some shapes have a line (or lines) of symmetry sometimes called 'mirror lines'.
In each case, if you stood a mirror on the line of symmetry, the shape
would look unchanged. (You can check this by using a mirror, or by
tracing a shape and folding it along the mirror line.)
Patterns can also be symmetrical
<<< <<<
<<< <<<
**** +++ ****
****************
**** +++ ****
Draw the line(s) of symmetry on the shapes above
A
shape
with
What is a
polygon?
many
sides
and
angles.
Regular polygons are a never-ending
series of shapes with one special feature
All the sides and angles
are the same size.
Do you know any regular
polygons?.
Here are some a regular
polygons?
Equilateral Triangle
Square
3 sides
4 sides
3 equal angles
4 equal angles
Hexagon
Octagon
6 sides
8 sides
6 equal angles
8 equal angles
Click anywhere on the page until you fill all the boxes
What are the properties
of these regular polygons?
Pentagon
A pentagon has 5 equal
sides and 5 equal angles
Heptagon
A heptagon has 7 equal
sides and 7 equal angles
Decagon
A decagon has 10 equal
sides and 10 equal angles
Nonagon
A nonagon has 9 equal
sides and 9 equal angles
Write your answers and check them by clicking 4 times
• A circle is a flat round shape.
• The distance from the centre to the
outside of the circle is always equal.
Circle Vocabulary
A circle has one side around the
outside called the circumference
Diameter is any line across the
circle that passes through the
centre of the circle
Radius is any line that is drawn
between the centre of the circle to
the circumference
Parallel Lines
Two lines are parallel if they are always the
same distance apart. This means they will
never meet even if they are extended
<
<
<
The arrowhead indicate
that these two lines are
parallel
Parallel Lines
Some shapes have 1 or 2 pairs of parallel
lines
<
<
<
<
<
<<
<<
<
<
The arrowhead indicate
that these two lines are
Sometimes <<
arrowheads are used to
show a second pair of
parallel lines
2D ( 2 dimensional)
Here is a line. This has one dimension (length)
All flat shapes have two dimensions,
length and width (breadth).
So they are called 2D.
What is an angle?
When two lines join two angles are formed.
When two lines intersect 4 angles are formed
X
X
X
Angles are measured with a protractor
1200
600
Two angles are formed. One angle is 1200 and the other is 600.
Together they make 1800.
Angles are measured with a protractor
A right-angle is 90o
Angles are measured with a protractor
Two right-angles are 180o
Four right-angles are 360o
A circle has 360o around its centre point
Two right-angles are 180o
Four right-angles are 360o
What is a complex shape?
A complex shape is a shape that can be broken into
smaller shapes. What shapes can you see in these
complex shapes?
Recap
1. What is a polygon?
2. What is a regular polygon?
3. Name 6 regular polygons.
List their properties
Next
Recap Answers
1.
A polygon is a many sided shape
2.
A regular polygon is a shape with equal sides and equal angles
3
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Any of the following:
Equilateral Triangle – 3 equal sides & angles
Square – 4 equal sides 4 right-angles
Pentagon – 5 equal sides & angles
Hexagon – 6 equal sides & angles
Heptagon – 7 equal sides & angles
Octagon – 8 equal sides & angles
Nonagon – 9 equal sides & angles
Decagon – 10 equal sides & angles
2D shapes – words – student record 1
Two Dimensional (2D)
length
width
side
angle
right-angle
parallel
2D shapes – words – student record 2
tessellation (to tessellate)
symmetrical (symmetry)
regular polygon
complex shape
radius
diameter
circumference
What shapes
can you see in
this picture?
What shapes can you see in this picture?
What shapes can you see in this picture?