As students enter the room, the teacher will display the bell ringer on the interactive whiteboard. The students will write their answers on their own paper. The teacher will make an informal assessment. Students must be able to solve multi-step equations in order to solve systems of equations by substitution. The teacher will solicit students to answer the bell ringer.
*The lesson will be taught in one class period.*
1. The teacher will start the video from Khan Academy: https://www.khanacademy.org/math/cc-eighth-grade-math/cc-8th-systems-topic/cc-8th-systems-with-substitution/v/the-substitution-method.
2. The teacher can show many types of examples. The website has lines in standard form as well as y-intercept form. The teacher will stop the video and revisit the concept of solving in terms of "y" or "x".
3x + 6y = -9
3x + 6y - 6y = -9 - 6y subtract 6y from both sides
3x = -6y - 9 put the "y" term in front
3x/3 = -6y/3 - 9/3 divide everything by 3
x = -2y - 3 solved for "x" in terms of "y"
3. The teacher will do an informal assessment to check for understanding. The teacher will start the video again.
4. As the video finishes the last example, the teacher will open the website, DESMOS.com (https://www.desmos.com/calculator). The teacher will type in the two equations and see where the two lines cross. The teacher will show the students that the solution will be the same. The teacher will tell the students that the method does not change the solution.
5. The teacher will hand out the worksheet, "Equations by Substitution" from the attachment section. The teacher will allow the students to work in groups with at least two technology devices. The students must show their work. One of the students in the group will use online graphing tool to check the answers. The teacher will monitor the groups and their discussions. The teacher may extend the time for some groups or assign a peer-tutor.
6. The teacher will check for understanding by asking the groups to work the problems on the interactive whiteboard.
*The lesson concludes day 2 and the next day will be elimination.*
The teacher will display the exit slip from the attachment section on the interactive whiteboard. The students will answer on their own paper and turn in when they leave the room.