Students revisit scale drawings in Topic C to solve problems in which the scale factor is represented by a percent (7.RP.A.2b, 7.G.A.1). They understand from their work in Module 1, for example, that if they have two drawings where if Drawing 2 is a scale model of Drawing 1 under a scale factor of 80%, then Drawing 1 is also a scale model of Drawing 2, and that scale factor is determined using inverse operations. Since 80% = 4/5, the scale factor is found by taking the complex fraction (1)/(4/5), or 5/4, and multiplying it by 100%, resulting in a scale factor of 125%. As in Module 1, students construct scale drawings, finding scale lengths and areas given the actual quantities and the scale factor (and vice-versa); however, in this module the scale factor is represented as a percent. Students are encouraged to develop multiple methods for making scale drawings. Students may find the multiplicative relationship between figures; they may also find a multiplicative relationship among lengths within the same figure.
Grade 7 Mathematics Module 4, Topic C, Overview
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