Videos to help Grade 6 students learn how to write expressions that involve addition and subtraction with numbers.

New York State Common Core Math Module 4, Grade 6, Lesson 9

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Common Core For Grade 6

Lesson 9 Student Outcomes

Students write expressions that record addition and subtraction operations with numbers.

Example 1

Create a bar diagram to show plus 3 plus 5.

How would this look if you were asked to show 5 plus 3?

Are these two expressions equivalent?

Example 2

How can we show a number increased by 2?

Can you prove this using a model?

Example 3

Write an expression to show the sum of m and k.

Which property can be used in Examples 1–3 to show that both expressions given are equivalent?

Example 4

How can we show 10 minus 6?

Draw a bar diagram to model this expression.

What expression would represent this model?

Could we also use 6 - 10?

Example 5

How can we write an expression to show 3 less than a number?

Start by drawing a diagram to model the subtraction. Are we taking away from the 3 or the unknown number?

What expression would represent this model?

Example 6

How would we write an expression to show the number c being subtracted from the sum of a and b?

Start by writing an expression for the sum of a and b

Now show c being subtracted from the sum..

Example 7

Write an expression to show c minus the sum of a and b.

Why are parentheses necessary in this example and not the others?

Replace the variables with numbers to see if c - (a + b) is the same as c - a + b.

Exercises

1. Write an expression to show the sum of 7 and 1.5.

2. Write two expressions to show w increased by 4. Then draw models to prove that both expressions represent the same thing.

3. Write an expression to show the sum of a, b, and c.

4. Write an expression and a model showing 3 less than p.

5. Write an expression to show the difference of 3 and p.

6. Write an expression to show 4 less than the sum of g and 5.

7. Write an expression to show 4 decreased by the sum of g and 5.

8. Should Exercises 6 and 7 have different expressions? Why or why not?

Lesson 9 Exit Ticket

1. Write an expression showing the sum of 8 and a number f.

2. Write an expression showing 5 less than the number k.

3. Write an expression showing the sum of a number h and a number w minus 11.