There are three parts to this resource:

Introduction to enlargements: This is an ideal resource for introducing pupils to the concept of enlargement and scale factor. .

Enlargements without a centre of enlargement: The resource enables the user to enlarge a given shape by dragging the vertices of a polygon.

Enlargements with a centre of enlargement: This is a very powerful resource that is perfect for exploring the enlargement of shapes using a centre of enlargement.

http://www.ngfl-cymru.org.uk/vtc/ngfl/maths/echalk/enlargement/index.htm