Operations with Rational Expressions

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SWBAT multiply, divide, and and subtract rational expressions

Big Idea

Operations with rational expressions are just like operations with fractions.

Warm Up

20 minutes

To get my students ready to perform operations on rational expressions, I engage them in a quick game of Kahoot! to practice simplifying rational expressions. Students can play Kahoot! on any internet enabled device and it is designed to be fun.

The Kahoot game Simplifying Rational Expressions is a set of 6 questions like those that students completed in class on the previous day.  I get this game started and then ask a student to lead it while I check the homework assignment.

Overview and Practice

50 minutes

To begin our study of operations with rational expressions, I ask students to look at WS Fraction Practice, from the previous lesson's warm-up.  I initiate a discussion about the process for performing operations with fractions.  Through this discussion, I want students to recall that

  • to multiply fractions, you multiply numerator by numerator and denominator by denominator then cancel common factors
  • to divide fractions, you turn it into a multiplication problem
  • to add or subtract fractions you need to get a common denominator.

I show students a few examples of operations with rational expressions, highlighting how the process is always the same as the one we use for fractions.

To practice these operations, students work in pairs to complete a domino-like game made from Rational Expressions Problem Cards with Answers.  To make the domino set, I print a question and answer together so that matching ends forms a line from "start" to "finish."  The first time this activity is used with students, the cards must be printed on colored card stock and cut out.

Exit Ticket and Assignment

20 minutes

To assess my students' progress in this skills-based lesson, I ask them to complete Exit Ticket Operations with Rational Expressions.  The 4 questions on this half sheet include multiplication, division, addition and subtraction of rational expressions.  I use the information collected from these exit tickets to determine how much review will be needed in the next class.

When students submit their exit ticket, they pick up the homework assignment, Worksheet Operations Rational Expressions, which will be checked in the next class.  The solutions to this worksheet will be available to students through Edmodo.