Today is rung 3 of 6 on this topic
Transformations, congruence and similarity
Can do: Performs and describes translations, rotations, reflections and dilations, and uses them to justify congruence and similarity.
Why it matters
It reframes congruence as "can be moved onto" rather than as a memorised list of rules, which makes proof intelligible next year.
What it looks like when it's wobbly
Can perform transformations but can't use them to explain why two shapes are congruent.
⏱️ Two-minute check
"Describe fully the transformation taking A to B." Then: "Are these two similar? Justify it."
Solid looks like: A complete description including centre or line, and similarity justified by a scale factor.
The full activity for this topic · 25 minutes
Move It Onto It
- 1Draw a shape and its image, then use tracing paper to physically find the transformation.
- 2Describe it fully — a rotation needs a centre, direction and angle.
- 3Chain two transformations and describe the single one with the same effect.
- 4Do a dilation and check which properties change and which don't.
- 5Explain congruence and similarity in terms of what transformations were needed.
If it's too hard
Single translations and reflections on a grid.
If it's too easy
Composite transformations, and dilations about a point other than the origin.
Say this
"A rotation needs three things: where round, which way, how far. Give me all three."