Even though this is Unit 5 in 8th grade, this is the unit I’ve done last the past couple years I’ve taught it. It just worked out that way my first year teaching 8th grade, and I liked it that way so I did it again this past year. I like having it at the end of the year because it’s a good way to review graphing lines.
I start the unit by spending a half day or so on just a review of graphing lines. I almost didn’t do that this year, but was SO glad that I did.
Then we spend some more time practicing. I’ve used this Desmos activity in the past.
After that we get into systems of equations that have no solution or infinite solutions. I usually start by putting up one of those types of problems without giving students any explanation.
Students have had a lot of experience solving problems with no solution or infinite solutions by this point in the year, so I usually have some students who come up with the fact that because both equations are the same line, there are infinite solutions.
I blogged here about how I introduce substitution to students. I’ve used this method 3 years in a row and am still amazed every. time. how smoothly it goes.
Here is the link to download some of the worksheets I use for this portion of our unit.