Transformations
Draw transformations online and have them instantly checked. Includes reflections, translations, rotations and enlargements.
Map Scales
Test your understanding of map scales expressed as ratios with this self marking quiz.
Similar Triangles
Understand similarity to calculate lengths in rotated and reflected triangles.
Similar Shapes
Questions about the scale factors of lengths, areas and volumes of similar shapes.
Blow Up
Click on all the points that could be the centre of enlargement of the shape if the image does not go off the grid.
This is the main Transum help video on Similarity.
Enlargement by a scale factor
A Maths teacher goes through the idea of enlarging a shape from a centre of enlargement.
Enlargements
A video showing how to enlarge a shape by a positive scale factor and a centre of enlargement. Includes a scale factor less than 1 and a centre of enlargement inside the shape.
Scale Factors Video
The scale factor, area factor and volume factor of similar shapes are quite different.
Negative Enlargement
A video from MathsWatch about Enlargement by a Negative Scale Factor.
Amplifying Alice
If the dimensions of an object double, its volume increases by a factor of eight.
Middle of Centres
The blue point is exactly in the middle of two red points. What are their coordinates?
Star Wars Day
Estimate the size of an alien given the size of their hand. This could be an introduction to scale factors.
12 items are currently in this category.
Teachers might find the complete Similarity Topic List useful.
When a shape is enlarged, the relationship between its lengths, areas and volumes is not always as obvious as you might expect. If the lengths of a rectangle are doubled, the new shape is similar to the original, but its area becomes four times as great. If the dimensions of a cuboid are doubled, the new solid is still similar, but its volume becomes eight times as great.
The activities provided here are designed to help pupils explore similarity and scale factors through diagrams, models and problem-solving. By working with a range of examples, they can develop a clearer understanding of how lengths, areas and volumes change when shapes are enlarged or reduced, and become more confident in answering questions on this topic.
Once positive integer scale factors have been mastered, pupils can go on to investigate fractional and negative scale factors, opening the door to even richer mathematical ideas.
