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OHS
SSM3/1: Angles making 360°
How many lines of symmetry?
Connection with centre angle?
Extend by asking pupils to predict shape with:
- 10 lines of symmetry? (centre angle 360 ÷
10)
- 12 lines of symmetry? centre angle 360 ÷
12)
- 20 lines of symmetry? (centre angle 360 ÷
20)
- 36 lines of symmetry? (centre angle 360 ÷
36) |
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- To be able to
recognise and visualise symmetry of 2-D shapes.
- & transformations of 2-D shapes.
- To use to solve problems by asking 'What if …?'. |
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as above
and
order of rotation |
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Show set of 4-6
shapes with various orders and lines of rotational
symmetry.
Q: Are some shapes more
symmetrical than others? Why do you think this?
Hand out some paper shapes, e.g. from:
OHS
SSM3/1: Angles making 360°
Ask pupils to:
a) - predict number
of lines of symmetry. Check
by folding.
b) - predict how many
times each matches original shape during a complete
turn. Check by rotating.
c) Which are easy to predict? Most difficult? Why?
d) - draw a parallelogram. Predict
order of rotational symmetry? Lines of symmetry?
Check. (Stress that
these 2 are often confused). Try a rhombus. |
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Investigate orders
and lines of rotational symmetry for different shapes,
including:
Triangles: scalene,
isosceles, equilateral.
Quadrilaterals: square,
rectangle, kite, rhombus, parallelogram, trapezium.
Other regular polygons: pentagons,
hexagons …
Other polygons …
Eg: What is the order of
rotation of a regular hexagon?
How many lines of symmetry?
OR
Animated
3-D Rotational Symmetry
- extension to 3-D. |
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Place
these 6 standard quadrilaterals in order of increasing
symmetry.
Justify your decision (by referring to order and
lines of symmetry).
Extend to regular polygons.
What is the most symmetrical
shape you can think of? (Circle). Why?
OR
Review properties of an
image after a reflection, translation or rotation.
(eg: Fwk: p.202 for Reflection). |
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OHS
SSM4/3: Symmetry in Tessellations
Q1:
How many lines of symmetry in these tessellations?
(A: 0 B: 2 C: 3)
Q2: How many within each square? (0)
Q3: Where there are no lines at all, why do these
tessellations still look symmetrical? |
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- To be able to
reflect, translate and rotate a 2-D shape (- all
quadrants).
- To explore these transformations and symmetries
using ICT.
- To be able to use language and notation of transformations.
- To be able to read and plot coordinates in all
four quadrants.
- To use to solve problems by asking 'What if …?'. |
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Review properties
of an image after a reflection, translation or rotation.
(eg: Fwk: p.202 for Reflection). |
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Explore all three
transformations using dynamic geometry software.
Eg:
Construct a triangle and
a line (- mirror line). Draw perpendicular line
from each vertex to mirror line. Move to other side
of mirror line. Use to identify position of each
reflected vertex. Join up to draw reflected triangle.
OR
Transformations
in Tessellations
Solve word problems involving reflections, translations
and rotations.
Ask 'What if …?'
questions to extend problems.
Eg: Pinboard investigation
(Fwk: p.186). |
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| Draw a shape. Image
after 180º rotation?Q: Which 2 rotations produce
the same final image? |
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