U3L1 Scale Drawings

In middle school, students studied scale drawings and dilations. In this lesson students review the definition of scale factor by comparing an example and a non-example of a scaled image. We define scale factor as the factor by which every length in an original figure is increased or decreased when making a scaled copy. In the subsequent activities students practice dilating points and figures. We define dilation as follows: A dilation with center P and positive scale factor k takes a point A along the ray PA to another point whose distance is k times farther away from P than A is. In this lesson students begin to identify the properties of dilations (A dilation takes a line not passing through the center of the dilation to a parallel line, and leaves a line passing through the center unchanged. The dilation of a line segment is longer or shorter according to the same ratio given by the scale factor.) but they do not formalize them until a subsequent lesson. This activity includes lesson summary videos and practice problems 

By JOEL NELSON