7th Grade Math

Expressions

PART A B C

Multi-Part

Lesson 1

Get ConnectED

D

GLE 0706.2.2

Understand and work with

the properties of and

operations on the system of

rational numbers. SPI 0706.2.1

Simplify numerical expressions

involving rational numbers.

Also addresses GLE 0706.1.7,

SPI 0706.2.3.

Lesson 1B Expressions 29

Numerical Expressions

SPORTS The Kent City football team made one 6-point touchdown

and four 3-point field goals in its last game. Megan and Dexter each

used an expression to find the total number of points the team scored.

Megan

6 + 4 · 3 = 6 + 12

= 18

The team scored 18 points.

Dexter

(6 + 4) · 3 = 10 · 3

= 30

The team scored 30 points.

1. List the differences between their calculations.


2. Whose calculations are correct?


3. Make a conjecture about what should be the first step in
   simplifying 6 + 4 · 3.

The expression 6 + 4 · 3 is a numerical expression. To evaluate

expressions, use the order of operations. These rules ensure that

numerical expressions have only one value.

Order of Operations

1. Evaluate the expressions inside grouping symbols.


2. Evaluate all powers.


3. Multiply and divide in order from left to right.


4. Add and subtract in order from left to right.

Use Order of Operations

Evaluate 5 + (12 - 3). Justify each step.

5 + ( 12 - 3 ) = 5 + 9 Subtract first, since 12 - 3 is in parentheses.

= 14 Add 5 and 9.

Evaluate 10 - 32 + 7. Justify each step.

10 - 32 + 7 = 10 - 9 + 7 Find the value of 3^2.

= 1 + 7 Subtract 9 from 10.

= 8 Add 1 and 7.

Evaluate each expression. Justify each step.

a. 39 ÷ (9 + 4) b. (5 - 1)^3 ÷ 4

Main Idea

Evaluate expressions

using the order of

operations.

Vocabulary

numerical expression

order of operations

V

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