3.9 True or False Number Sentences

Homework Review

Mental Math Solve. Show your work.

Stephanie, Kelly, and 3 friends are going to the aquarium. Tickets cost $2 each. What is the total cost? _______

Alyssa runs 3 miles every day. About how many miles does she run in a month? _____

Mrs. Abramson spent $17.25 for groceries. How much change did she get from a $20 bill? _____

Math Message

In your Math Notebook, write one true sentence and one false sentence.

Exploring the Meaning of Number Sentence

The sum of five and eight is equal to thirteen.

What is another way to write this sentence?

How can we write this sentence in words?

How about this one?

What is a Number Sentence?

A number sentence is a shorthand way for sentences written in words.

Words are replaced by mathematical symbols

•Numbers made from the digits 0 through 9.

•Operation symbols: +, -, * (or X), / (or ÷)

•Relation symbols: =, <, ad >.

Using symbols is easier to understand than words.

Deciding Whether a Number Sentence is True or False

Is this number sentence correct?

If it is correct, you can also say thatis a true number sentence.

If you multiply or add equals to equals, you get equal quantities.

Is this number sentence correct?

Is this number sentence correct?

If it is incorrect, you can also say thatis a false number sentence.

Let’s practice…Decide if the number sentences are true or false.

Let’s think!

Can you tell it is true or false before subtracting?

Can you tell whether it is true or false before adding?

Why can’t you tell?

How could we change them to make them true number sentences?

Practicing with Number Sentences

Solve problems 1-8 on MJ page 69, with

a partner.

SEPARATE.Then complete 9 and 10 ALONE.

COME TOGETHER.

Exchange journals to solve each

others problems in number 10.

Tonight’s Homework

Math Boxes