Starter quiz
- Which triangle is congruent to triangle T?
- A ✓
- B
- C
-
- Which triangle is similar to triangle T, but not congruent to triangle T?
- A
- B
- C ✓
-
- Rectangle A has lengths 3 cm by 6 cm. Rectangle B is congruent to rectangle A. One of the lengths of rectangle B is 6 cm, so the other length is ______ cm.
- '3' ✓
- The image shows two congruent pentagons. What is the value of ?
- 2.9
- 3.2 ✓
- 3.4
- 4.8
-
- The image shows two similar hexagons. The size of the angle is ______°.
- '153' ✓
- Rectangle A has lengths 3 cm by 6 cm. Rectangle B is similar, but not congruent, to rectangle A. One of the lengths of rectangle B is 6 cm, so the other length is ______ cm.
- '12' ✓
Exit quiz
- The two shapes in the image are __________.
- congruent
- similar ✓
- neither congruent similar
-
- The two shapes in the image are __________.
- congruent
- similar
- neither congruent or similar ✓
-
- The two shapes in the image are __________.
- congruent ✓
- similar
- neither congruent or similar
-
- ∆ABG and ∆ADE are __________.
- congruent
- similar ✓
- neither congruent or similar
-
- ∆ADE and ∆ACF are __________.
- congruent
- similar
- neither congruent or similar ✓
-
- ∆ABC and ∆CDE are __________.
- congruent ✓
- similar
- neither congruent or similar
-
Worksheet
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Presentation
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Lesson Details
Key learning points
- If two shapes are congruent, then they are similar.
- Congruent shapes have a scalar of one.
- A ratio table can be a helpful tool for checking the multipliers.
- The multiplicative relationship between the sides of the object is preserved in its image.
Common misconception
Pupils may mix up the meanings of congruence and similarity or struggle with the hierarchy of their nested sets (e.g. thinking that all similar shapes are congruent rather than the other way around).
Frequently refer to a Venn diagram showing the set of congruence shapes inside the set of similar shapes when examining pairs of shapes.
Keywords
Similar - Two shapes are similar if the only difference between them is their size. Their side lengths are in the same proportions.
Congruent - If one shape can fit exactly on top of another using rotation, reflection or translation, then the shapes are congruent.
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