If you are citizen of an European Union member nation, you may not use this service unless you are at least 16 years old.
You already know Dokkio is an AI-powered assistant to organize & manage your digital files & messages. Very soon, Dokkio will support Outlook as well as One Drive. Check it out today!

7-GM-4-2

Page history last edited by Brenda Butz 6 years, 3 months ago

7.GM.4.2 Apply proportions, ratios, and scale factors to solve problems involving scale drawings and determine side lengths and areas of similar triangles and rectangles.

In a Nutshell

Similar figures are those who have the same shape and who have corresponding sides that are proportional. Missing corresponding side measurements can be determined if a scale factor is available or can be found based on information from the other sides as can area.

Student Actions	Teacher Actions
Develop mathematical reasoning by determining the lengths and areas of similar triangles and rectangles using proportions, ratios, and scale factors using a variety of strategies. Develop the ability to communicate mathematically when triangles and rectangles area similar and when they are not.	Use questioning to elicit evidence of students’ thinking as they determine side lengths and areas using ratios, proportions, and scale factors. Pose purposeful questions to students about how they determined measurements. Implement tasks that promote reasoning and problem solving finding the missing lengths using a variety of strategies.
Key Understandings	Misconceptions
Given a scale factor, tell how many times the original figure can fit in the new image. Find dimensions of the real image if given the scale drawing of it and the scale factor. Create and use ratios to find corresponding side lengths. Determine and list corresponding sides and angles of similar figures.	Students may struggle when they are given the area and are asked to find one length. Students sometimes do not realize how to work backwards to find this. Students may forget the difference between the area formula of a triangle and the area formula of a rectangle.