In this Warm-up, students think about how the size of the scale factor impacts the dilation of a figure. While students may notice and wonder many things about the image, the fact that it shows several dilations of one triangle, all with the same center but different scale factors is the important discussion point.

When students articulate what they notice and wonder, they have an opportunity to attend to precision in the language they use to describe what they see (MP6). They might first propose less formal or imprecise language, and then restate their observation with more precise language in order to communicate more clearly.

In the digital version of the activity, students use an applet to adjust the scale factor of a dilation. The applet allows students to instantly see how increasing or decreasing a scale factor impacts the dilation of a triangle.