Page 103 - Knowledge Organiser Yr7 24-25

Knowledge Base: Mathematics TOPIC 12: Symmetry Year 7 | Summer Term 2
By the end of this topic you should be able to:
• Find the order of rotational symmetry
• Reflect a shape
• Find the line of reflection
• Rotate a shape
• Translate a shape
• Know why shapes tessellate
• Tessellate a shape
Vertex
A corner of a 2 dimensional shape
A square has 4 vertices
Language
Meaning
Example
Object
The object is the shape before the transformation
Image
The image is the shape after the transformation
Transformation
A change in the position or size of a shape that follows set rules
Reflections, rotations and translations are all transformations
Rotation
A transformation that turns an object through a given angle about a given centre of rotation
Turning this page through 90° clockwise about its bottom right corner is a rotation
Reflection
A transformation which flips an object over a mirror line
Looking at this page in a mirror is a reflection
Important things to remember:
1) Don’t say ’mirrored’ say reflected. Provide the equation of the line of reflection
2) Don’t say ‘turned’ say rotated and provide the angle, direction and centre of rotation
3) Don’t say ‘moved’ say translated and provide the vector
Translation
A transformation which slides/moves an object
Sliding this page across the table is a translation
Translate 1
Reflective Symmetry
Another name for a power such as ‘squared’ or ‘to the power of 5’
A rectangle has reflective symmetry in both the horizontal and vertical lines through its centre
Rotation Symmetry
To replace a letter in an algebraic expression with a number
A rectangle has rotational symmetry of order 2 about its centre
Tessellation
A tiling pattern that doesn’t have any gaps
A tessellation made from parallelograms
Worked examples
Order of Rotational Symmetry?
4
By
3 0
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