Mathematics (2019) Grade(s): 7

MA19.7.17

Solve problems involving scale drawings of geometric figures, including computation of actual lengths and areas from a scale drawing and reproduction of a scale drawing at a different scale.

Unpacked Content

Knowledge

Students know:
  • how to calculate actual measures such as area and perimeter from a scale drawing.
  • Scale factor impacts the length of line segments, but it does not change the angle measurements.
  • There is a proportional relationship between the corresponding sides of similar figures.
  • A proportion can be set up using the appropriate corresponding side lengths of two similar figures.
  • If a side length is unknown, a proportion can be solved to determine the measure of it.

Skills

Students are able to:
  • find missing lengths on a scale drawing.
  • Use scale factors to compute actual lengths, perimeters, and areas in scale drawings.
  • Use a scale factor to reproduce a scale drawing at a different scale.

Understanding

Students understand that:
  • scale factor can enlarge or reduce the size of a figure.
  • Scale drawings are proportional relationships.
  • Applying a scale factor less than one will shrink a figure.
  • Applying a scale factors greater than one will enlarge a figure.

Vocabulary

  • Scale drawing
  • Reproduction
  • Scale factor
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