Lesson 10: Proportions
A Cheat Sheet is an all-in-one, single-page graphic organizer covering the big topics in the Algebra 1 curriculum. Each Cheat Sheet includes important vocabulary, key concepts, and guided examples. There is a set of Practice Problems included with each sheet that provides leveled and skill-based practice. Included in the download is a PDF and editable WORD version of the Cheat Sheet and Practice Problems, along with a full answer key.
This lesson begins with writing ratios three different ways. The concept of “cross products” is used to teach students to test for a proportion by identifying if the two products are equal. The cross products principle is applied to help students solve proportions for missing variables. Similar figures are introduced and students setup and solve proportions to find missing side lengths for various polygons. The remainder of the lesson involves applications of proportions from using scales, to similar figures, to ordinary proportional applications for solving real-world problems. The Practice Problems correspond to the Cheat Sheet and give students several problems to process each part of the lesson.