Khan Your Way Into Solving a System of Equations Using Elimination

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SWBAT solve a system of equations using eliminations, and using the hints off Khan Academy and the videos to scaffold their learning if necessary.

Big Idea

The idea of this lesson is to provide students with an alternate teaching method by using Khan Academy to gain interest, comprehension, and scaffolding for differentiated learning.

Warm up

10 minutes

I plan for this Warm up to take about 5 minutes to complete and about 5 minutes to discuss with the students in order to check their own responses.  This warm up shows students that when solving a system of equations by linear combination, multiplication and addition are the two math operations that are used.  Also, students are reminded that when performing a math operation throughout the entire equation, it produces an equivalent equation.  

As they work, students should discover that a multiple of an original equation will be the same line. When students recognize an equation as a multiple of another equation, I teach them to describe the equations as equivalent.  And, we discuss the fact that a system of equivalent equations has infinitely many solutions. 

Students also learn that the sum of a system of equations has the same solution as the system of equations. 

Khan Academy Practice

30 minutes

When beginning to use Khan Academy with students, I make sure that they login so that I can later check their progress online.  

Teacher's Note: I previously have signed up as a coach on Khan Academy using my gmail account.  I created my classes, and Khan Academy provides a code for me to give to the students for each class.  All of my students also have gmail accounts through the school and I have each sign up for Khan Academy using his/her gmail account. When logged in, they select add a coach, and enter the code that I give them.  

My students have previously been exposed to the elimination and linear combination methods in a previous lesson, Quarters and Dimes. I begin with a KA lesson on simple elimination. At first, students take notes as I project the website on the projector.  I plan to work 2 examples with the students.  

For this assignment, I want students to practice solving a system of equations by simple elimination.  The students are required to solve 5 problems in a row correctly, or Khan Academy assigns more problems that are needed.  If the student continues to struggle, they may raise their hand and ask for help. I help them one on one, or, I suggest that they watch one of the videos directly above the practice lesson.  

Throughout this lesson, I require my students to have a pencil and paper. I want them to show all of their work on the papers that they will hand in once the assignment is completed. If I see a problem with all of the students, I stop the class, and teach that problem or part of the problem needed.  

In case some students finish quickly, I am prepared to assign a more advanced lesson: systems of equations with elimination on Khan Academy.  I am also aware that some students will need the full 30-minutes to complete the first assignment.

After class, I will check their progress on the first assignment when I log in as a coach. 


10 minutes

I have students complete the Summary on elimination with about ten minutes left in the period. I want the students to carefully describe their process and express their reasoning on the given problem.   I walk around the room as they work to help students that have difficulty writing about the process. This summary task helps students to focus on the steps used to solve problems as we close out the lesson.