Rational Numbers: Subtracting

Objectives:

• Students will review the basics of subtracting decimals, fractions and mixed numbers.

• Students will review the rules for subtracting negative numbers.

• Students will learn how to subtract rational numbers.

• Students will practice all of these skills.

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:

I. Introduction

In our last lesson we worked on adding rational numbers. Today, we are going to learn how to subtract rational numbers.

One of the things that we learned about in the last lesson is that when you are adding rational numbers, you often have to keep several different rules in mind. For example, when we were adding decimals, we had to keep in mind the rules for adding decimals, and then we had to factor in whether there were any negative decimals before we arrived at our final answer. The same thing is going to be true of subtraction.

When we are subtracting rational numbers, we need to keep in mind the rules of subtraction with the rules of positive and negative numbers. Let us begin.

II. Subtracting Rational Numbers

Let us review how to subtract rational numbers that are also negative. Let us look at an example and then review the rule. Again, we are thinking of this in terms of gains and losses.

Continued...