# Lines Around the World: Combining and Graphing Integers on a Number Line

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## Objective

SWBAT combine two or more integers by writing numerical expressions and plotting them on a number line

#### Big Idea

Students move from station to station individually or in partners graphing integer addition sentences and writing addition expressions

## Do Now

10 minutes

Students enter the class and find a “Do Now – Pop Quiz” on their desk that will include 5 integer combination questions. The questions will assess student knowledge of combining integers with opposite signs and integers with the same sign(i.e. 16 + (-5) and -6 + (-8)). The pop quiz will help me generate a list of students still struggling with integer addition. Students who have not mastered this concept will be encouraged to work in groups so that I can work with them more closely. There are two forms of the quiz, A and B. The letters are indicated at the top right hand corner of each quiz. I will have answers ready to check as students finish.

## Class Notes + Intro to Lesson

10 minutes

Students are instructed to take out their homework from the previous night. They are also instructed to fill out their heading in their notes and to copy the aim off the power point.

We begin by reviewing the answers to the homework assignment from the previous night. That assignment included 6 word problems. Students were responsible for writing and evaluating addition expressions to represent each word problem (i.e. a “plane descends 1200 feet and then ascends 500 feet”; Glencoe Workbook online, pg 18). I review the answers to the homework by asking students to read each word problem. After a student reads a portion that could be represented using an integer I ask them to stop and I show everyone which integer represents that part of the problem. Some students may ask about the relationship between adding the inverse and subtracting. I simply state that their number sentence gives the same result, but they must write an addition sentence because of the directions. We discuss the answers to each expression by thinking about the use of counters we explored the previous day. I stop when we get to the golf problem to explain the rules of golf. Many students do not understand the idea of “par”, so I make sure to make time to explain golf, how it is played, and the meaning of “par”. To check for understanding, I ask a volunteer to explain what “0 par” would mean, as well as “1 over par” and “1 under par”. I also point out that in golf you want to get a negative score or zero, not a positive score. Students are asked to explain why one would want a negative or zero score.

After the homework has been reviewed, we fill out the Cornell Notes. I review the position of negative and positive integers in relation to zero for both horizontal and vertical lines. Then, we complete two sample problems together: one that asks students to draw the “arrow annotation” given an expression and another that gives the arrow notation and asks students to write an expression. If there is time, I also show students how to draw arrow notation for combining two negatives. Student questions are answered if there are many, or if there are only a few, they are encouraged to ask their questions during the game.