Ratios and Proportions: Proportions

Objectives:

• Students will learn how to figure out if two ratios form a proportion.

• They will learn how to do this through reducing and cross-multiplying.

• Students will learn how to solve a proportion for an unknown.

• They will practice both of these new skills in their independent work.

Suggested Grades:

Sixth Grade - Seventh Grade - Eighth Grade - Ninth Grade - including special education students

Lesson Procedure:

Print the classroom lesson plan and worksheet questions (see below).

Lesson Excerpt:

II. Proportions

- "Today we are going to start talking about proportions. A proportion is also a way of comparing. But a proportion is a way of comparing two ratios. If the ratios are equal, then we can say that they are "in proportion" or "form a proportion." Copy these notes in your notebooks."
- On Board: A proportion shows that two ratios are equal.
1/6 = 2/12
- "In this example, we are comparing the two ratios. We are comparing 1/6 and 2/12. In this case, these two ratios form a proportion because they are equal. There are two different ways to tell if two ratios form a proportion. One is to cross multiply, and if the cross products are equal, then the two ratios form a proportion. The other is to reduce both ratios into their simplest forms. Again, if they are equal in their simplest form, then the two ratios form a proportion. Here are the notes to copy into your notebooks."

Continued...