Algebraic Expressions Everyday Math Lesson 10.3

Lesson Objectives I can identify and use patterns in tables to solve problems I can write algebraic expressions to model rules I can use variables to write number models that describe situations

Mental Math

Math Message ( 3 minutes) Joe and Maria are 5 th graders. Joe is 2 inches taller than Maria. Make a table of 4 possible heights for Joe and Maria.

Math Message Follow-Up (5 minutes) How tall is Joe? What does his height depend upon? How tall is Maria?

Introducing Algebraic Expressions * The table of Maria and Joe’s height is similar to a “What’s My Rule?” table. – What was the rule for Maria and Joe’s table? Let’s represent Joe’s height using an algebraic expression. (“M” represents Maria’s height) M + 2 M

Turn to pg. 218 in your SRB. Study the examples of expressions that algebraic and those that are not. – What’s the difference???? Expressions use operation symbols (+, -, *, /) to combine numbers, but algebraic expressions combine variables and numbers. KEY POINTS: – A situation can be represented in several ways (words, table, or symbols) – Algebraic expressions use variables and other symbols to represent situations – To evaluate an A.E means to substitute values for variables and solve.

Practice! Propose algebraic expressions to fit the situations Sue weighs 10 pounds less than Jamal. If J= Jamal’s weight, then J-10 represents Sue’s weight. Isaac collected twice as many cans as Alex. If A= the number of cans Alex collected, then 2 * A, (or 2A) represents the number of cans Isaac collected. There are half as many problems in today’s assignment as there were in yesterday’s. If Y= the number of problems in yesterday’s assignment, then there are ½ Y, ½ * Y, or Y/2 problems in today’s assignment.

Algebraic Equations Expressions can be combined with relation symbols (=, ) to make number sentences. – X + 2 = 15 – 3y + 7 < 100 * These are called “Algebraic Equations” (number sentences that contain algebraic expressions)

Writing Algebraic Expressions Turn to pg. 341 & 342 in your journal. Let’s go over problem 1 Complete the statements on both pages with a partner. When you are finished, complete the “What’s My Rule” on pg. 343.

Independent Work On your own at a level 0, complete Math boxes on page 344. When you are finished, you may work on Study Link 10.3