Do you view proofs as an essential geometric skill? The resource builds on an understanding of dilations by proving the Dilation Theorem of Segments. Pupils learn to question and verify rather than make assumptions. 

Concepts

dilations, scale factors, scale drawings

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Additional Tags

math

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Instructional Ideas

• Use graph paper to explore points other than endpoints of segments or vertices of polygons that undergo a dilation
• Form collaborative groups to tackle the provided problem set questions

Classroom Considerations

• Features a formal proof analysis of the dilation theorem of segments; those uncomfortable with proofs will need more time and guidance
• The seventh lesson in a series of 36

Pros

• Makes connections from dilated segments to polygons, including trapezoids and parallelograms
• Provides suggestions for scaffolding and questioning

Cons

• None

Common Core

HSG-SRT.A.1.a HSG-SRT.B.4 MP3