##
* *Reflection: Discourse and Questioning
Linear Expressions and Word Problems - Section 2: Gallery Walk and Discussion

Here is an example of incorrect matches between expression and statement and how we discussed these ideas.

Statement A - Adult tickets were $15 each. Student tickets were $10 each. We bought several adult tickets and one student ticket.

The correct expression is 15x + 10. The most common incorrect expressions were 10x + 15 and 15x + 10x.

Several students picked 10x + 15 as the matching expression.

-> "What do the 10, 15, and x represent in the problem?" [student ticket, adult ticket, number of tickets]

-> "How many adult tickets were bought? How many student tickets were bought? How do we find the total cost of adult tickets?"

If students picked 15x + 10x.

-> "What does this expression tell us about the number of adult tickets and student tickets that were bought?" [The same amount of each type of ticket was bought.]

It was always helpful to replace the variable with an actual value.

-> "How much would we spend if we bought 3 adult tickets and one student ticket? How would you calculate this?"

Students were able to see their misconceptions through this questioning. Now I just have to get students comfortable with asking these types of questions for themselves!

*Talking Through Misconceptions*

*Discourse and Questioning: Talking Through Misconceptions*

# Linear Expressions and Word Problems

Lesson 4 of 20

## Objective: SWBAT write and match linear expressions to word problems

## Big Idea: Students analyze and match algebraic expressions to word problems. Students then write some algebraic expressions to represent word problems.

*55 minutes*

#### Introduction

*15 min*

I will begin with a question: "What does the term algebraic expression bring to mind?" I will have a simple word web organizer drawn on the SmartBoard. As students contribute answers, I will draw in the connections on the word web. Hopefully students come up with answers like: they involve variables, numbers, operations, represent word problems, etc...

This is not only to assess prior knowledge but to also have students show see how much they already know about expressions. I will try (emphasis on "try") to make every relevant response a correct answer so that students feel free to contribute their thoughts. Almost every time I do this, I am pleased with how much useful information students are able to contribute.

Then I will present four simple statements in the resource. We will work together to match the statement to the expression. For each expression, we will discuss what the variable means in context to the verbal statement.

Note that a couple of the statements may have more than one matching expression depending on the perspective you take in the problem.

All of this is a simple exercise to prepare students for the work ahead in the next section. This is also an exercise in **MP1 ** - specifically connecting the relationship between verbal descriptions and expressions.

#### Resources

*expand content*

#### Gallery Walk and Discussion

*20 min*

Logistics:

Before the lesson:

I'll place the 6 verbal statements throughout the room.

I'll divide the class into 6 groups based. (These may be mixed ability groups)

I'll need enough sticky notes for each student to have 6.

During the lesson:

I'll have students copy the 6 algebraic expressions onto their sticky notes - one expression per sticky note.

I'll explain that they will rotate with their groups to the statements around the room. They are to pick the expression that they think best matches the statement. They should place their sticky note on that expression.

I will set the timer for about 1-2 minutes before rotating. Of course, I'll judge whether or not it appears they need more or less time and adjust accordingly.

Once all of the statements have been placed we will discuss the responses.

I purposely did not include a question with the statements, so that for each I can ask: What question could the expression answer? For each expression we will discuss what each part (coefficient, constant, variable, operations, etc) represents.

I expect for there to be some disagreement over several of these since they all use 10, 15 and x. Students will often confuse 10x + 15 with 15x + 10 or even 10x + 15x. This activity should bring about all of the misconceptions.

*expand content*

#### Writing Expressions

*15 min*

Now students will have a chance to write algebraic expression to represent some word problems. I'll have students work for the first several minutes by themselves before they will be allowed to check in with a neighbor. The first 4 problems are 1-step expressions. The last two are 2-step expressions which is right where the common core expects 7th grade students to be. We will briefly discuss answers before beginning the exit ticket.

#### Resources

*expand content*

#### Exit Ticket

*5 min*

There are 4 question on the exit ticket. Two are multiple choice to represent the matching algebraic expressions to statements part of the objective. The other two are open ended to match the writing algebraic expressions to statements part of the objective. The first two problems are one-step expressions and the last two are two-step expressions.

A successful exit ticket will be measured as at least 3 correct responses out of 4.

#### Resources

*expand content*

I love the resources! It is always helpful to have more examples for word problems. I also really appreciate the well thought out exit ticket with multiple choice answers.

| one year ago | Reply

Thank you, I was trying to figure out a way to explain this to my students, I appreciate this!

| 2 years ago | Reply

Gallery walk gets the kids up and moving. Another great lesson!

| 3 years ago | Reply*expand comments*

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- LESSON 4: Linear Expressions and Word Problems
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- LESSON 14: Solve Two-Step Equations Using Inverse Operations
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