NY Next Generation Math NY-7.G.1

Math7th GradeDraw, construct, and describe geometrical figures and describe the relationships between them.

The Standard

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

New York State Next Generation Mathematics Learning Standards

Teacher's field guide

What This Standard Means

What Students Need to Do: Students use a drawing's scale to find actual lengths and areas. They also reproduce the same figure at a new scale while keeping all dimensions proportional.
What Mastery Looks Like: Given a rectangle drawn 3 centimeters by 5 centimeters at 1 centimeter to 4 meters, a student finds 12 meters by 20 meters and 240 square meters. The student can redraw it accurately at 1 centimeter to 2 meters.
Common Misconceptions: Students may reverse the scale ratio or apply it to only one dimension. They may multiply area by the linear scale factor instead of by its square.
How to Assess It: Show a 3-by-5-centimeter rectangle with a scale of 1 centimeter to 4 meters. Ask for its actual dimensions and area, then a redraw at 1 centimeter to 2 meters.

Lesson moves

Ways to Teach It

Measure a tabletop, choose a scale, and draw it on grid paper with every side labeled.
Ask, "Why does doubling every side length make the area four times as large?"
Match cards showing a scale, drawing dimensions, actual dimensions, and area, then explain each complete set.
Use a room floor plan to calculate the actual length of one wall and the area of the room.

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