# Integers in the Real World

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## Objective

SWBAT use integers and number lines to represent quantities in real-world contexts.

#### Big Idea

Rational numbers and number lines can be used to represent real world situations.

7 minutes

Students work in pairs on the Think About It problem.  The point of this problem is to have students thinking about integers in a real-world context.

After 2-3 minutes of partner work time, I have students share out what they came up with for the number sentences.  I also use this conversation as a way to have students articulate that integers are all positive and negative counting numbers, including zero (which they learned in the previous lesson).

In the conversation about the problem, I want the students to conclude that even though Emari started with less money, he ends up with more money in his account than Elana.

## Intro to New Material

15 minutes

In the Intro to New Material section, students will be exposed to both horizontal and vertical number lines, applied to real-world situations.

To start this section, we work with the Think About It problem.  Students are not likely to be familiar with the word 'withdraw,' so we spend time talking about what that means with money.  We also talk about not using '+' in front of positive numbers - it is assumed that numbers are positive, so we don't need it.

For the number line in this situation, we'll place 0 ("zero") in the middle of this number line, and then count by 1s, in both directions.  I do make sure, though, that students see a variety of number lines in this unit (and beyond!) - I don't want students thinking that the origin always has to be in the middle of the visual.  I also want students in the habit of checking the scale on a number line, and not working under the assumption that the hatch marks count by ones.

After students read the second problem, I have them paraphrase what the problem is asking us to do. This is an important step in the sense-making process.  Once students have identified that we need to represent the problem with integers, plot the numbers, and interpret the 0, I then have students turn to their neighbor and talk about why a vertical number line makes sense in this situation.  I guide students through this problem.

## Partner Practice

15 minutes

Students work in pairs on the Partner Practice problem set.

If, during the Intro to New Material section, it feels like students might need more support from me while working on a vertical number line, I will have pairs complete only Problem A in this problem set.  We'll come back and check in before I release them to partner practice with less support from me.

As students work, I circulate around the room and check in with each group.  I am looking for:

• Are students annotating/paraphrasing the question, using + and - for each integer
• Are students drawing their number lines with hatch marks evenly spaced and correctly labeled?
• Are students drawing vertical number lines when it fits the context?
• Are students interpreting the given contexts correctly?
• Are students answering in complete sentences?

• How did you know to represent the context with that integer?
• How did you know to draw a vertical/horizontal number line?
• How did you know to label the number line with those integers?

After 10 minutes of partner work time, students complete the Check for Understanding problem independently.  I then show one student's work on the document camera.  The student explains his/her thinking.  The class then offers the student positive and constructive feedback.

## Independent Practice

15 minutes

Next I have my students work on the Independent Practice problem set.  The problems in this set expose students to many vocabulary words that they may not be familiar with.  I keep a vocabulary list on the board (or a wall) throughout this unit. Many of my students will access it as they work on these tasks.

Problem 5 is a novel problem, and students may be stumped when they first see it.  As I circulate, I'm looking to see that students are working out the different pieces of this problem and are plotting them correctly on the number line.

Problem 9 asks students to apply what they learned previously about absolute value to a real-world situation.

## Closing and Exit Ticket

8 minutes

After independent work time, I have the class come back together.  I have three students share out their scenarios for Problem 10 and three students share out for Problem 11.  After each share, the class votes with their thumbs about whether or not the scenario represents the appropriate integer.

Students work independently on the Exit Ticket to close the lesson.