## Describe the Expression

## Opening

# Describe the Expression

- Which of these expressions shows “subtract 3 from
*x*”?

*x *− 3 or 3 – *x*

- Which of these expressions shows “subtract 3 from
*x*”?

*x *− 3 or 3 – *x*

Use words to describe algebraic expressions.

Match each algebraic expression card with a written description card.

INTERACTIVE: Matching Algebraic and Written Expressions

Replace the words “any number” in the descriptions with the letters in the algebraic expressions.

Prepare a presentation about the strategy you used to match cards.

- Make up a verbal description of a multi-step calculation that has the words “any number” in it, and then write the algebraic expression for the calculation.

Takes notes about the strategies your classmates used to match algebraic expressions with written expressions.

As your classmates present, ask questions such as:

- What strategy did you use to complete the card sort?
- Which cards were easiest to match? Which cards were most difficult to match?
- In the challenge problem, was it difficult for you to write the description first, and then write the algebraic expression? Do you think it would have been easier to write the algebraic expression first?

**Read and Discuss**

- In algebraic expressions, letters stand for numbers. You can use any letter to represent an unknown value. A letter used in place of a number in an expression is called a
*variable*. - Words can be used to describe algebraic expressions.
- An algebraic expression combines both numbers and letters using the arithmetic operations of addition (+), subtraction (–), multiplication (⋅), and division (÷) to express a quantity.

Can you:

- Describe how letters are used in algebraic expressions?
- Describe what elements might be included in an algebraic expression?

Write a reflection about the ideas discussed in class today. Use the sentence starter below if you find it to be helpful.

**Something new I learned today about expressions is …**