Addition and Subtraction One Step Equations

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SWBAT solve one step equations using addition and subtraction

Big Idea

Students will formalize their understanding of the algebraic properties of equality by solving equations using addition and subtraction.


10 minutes

Students will complete the do-now in 4 minutes. I will then ask a student to come to the front of class to review the answers with the class. 

Next, a student will read the objective and question of the day to the class: SWBAT solve one step equations using addition and subtraction. I ask the students to tell me five things that they already know about equations. After students share their responses I will tell the class that an equation is a math sentence where both sides are equal to each other. To help students picture the property of equality, I will show the following example on my board:

Ms. Davis = (Picture of Ms. Davis)

I will then ask the students why this example qualifies as an equation.

Notes/Guided Practice

30 minutes

The major focus of the current unit is solving linear equations.  Because of the importance of this standard, I deliberately teach equation solving methodically and slow.

Before we begin any examples I tell the students that our priority over the next few classes will be to understand why specific operations work when solving an equation. I will insist that students show ALL work, and that we agree as a class to ban mental math until we are fluently solving equations.

For examples 1-3, I give students the value of x before we begin to de-emphasize the pursuit of the answer. At this point I will also make drawing a line through the equal sign and the variable/constant heading mandatory to embed this as a habit when students work (see add sub pic.JPG). This will seem overly tedious to my advanced students, but the payoff is huge when we begin solving multi-step equations.  Students can become easily overwhelmed then, and their problem solving becomes unorganized and messy.

For each example I will use a similar line of questioning:

  • What is the variable?
  • What operation is happening to the variable right now?
  • How can we undo a number plus four?
  • According to our heading, only variables belong on this side of the equation. Which number is variable? Which term does not belong on this side? How can we undo this step?
  • Does this answer make sense in the problem? If I plug this answer into the original equation are both sides still equal?

Slides 9 and 10 give an incorrect answer. A volunteer pair of students will come up to the board to lead the class through a discussion on the specific error made that led incorrect answer. The students will then call on other students to correct the mistake.  

Independent Practice

30 minutes

Students will work independently or in pairs on a one-step equations crossword. This is a great activity for students because the activity is self-checking. If the student's work produces an answer of four, but the answer space requires a five lettered number, students will automatically know that they have made a mistake and need to go back and check their work.

For this activity I insist that students work out each equation on the equation work space.docx document. Students should be drawing a line through the equal sign, and labeling variables/constant at the top of each equation.


10 minutes

I will ask two students to give a 15 second summary of what we learned in class today. I will ask a third student to share out one thing that makes this skill difficult, and one tip they would give a struggling student who was working on the same activity. I will then ask students if they see the importance of the Translating Verbal Expressions lesson in relation to what we have worked on today and to connect the two lessons together. Students will then complete AddSub One Step Equations EC.docx.