National Council of Teachers of Mathematics
Nctm: Illuminations: Scale Factor
Use this applet to investigate how changes in the scale factor influence the ratio of perimeters and the ratio of areas between two figures.
Khan Academy
Khan Academy: Dilations: Scale Factor
Find both the center and the scale factor of a dilation that maps a given figure to another one. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
CK-12 Foundation
Ck 12: Geometry: Polygon Similarity Study Guide
[Free Registration/Login may be required to access all resource tools.] This study guide looks at similar polygons, scale factor (ratio), and triangle similarity.
CK-12 Foundation
Ck 12: Geometry: Dilation
[Free Registration/Login may be required to access all resource tools.] In this lesson students explore geometric dilations. Students examine guided notes, review guided practice, watch instructional videos and attempt practice problems.
Science Struck
Science Struck: Similarity Statement in Geometry With Examples
Models how to write a similarity statement about different types of triangles and quadrilaterals.