Horizontal & Vertical LInes

This is another topic that students have seen before in 8th grade. But I find that students really don't understand how the simple equation of y = -2 or x = 4 result in a vertical or horizontal line. They are used to seeing those simple equations as solutions of equations in a single variable. So I have to remind them that we are now working on a coordinate plane and these are equations in two variables.

My advanced students are quick with this concept and remember it well from last year. All that we need to do is review with some ISN inserts. I LOVE the HOYVUX inserts I found via Sarah Hagan at Math=Love.

Since this is pretty quick I finish up class by giving them an investigation to get ready to talk more formally about linear functions. We buy this great red graph paper from GEYER and I give them a sheet for this investigation. It comes in 6 per side (front & back) or 3 per side (front & back). disclaimer: I do not profit from mentioning this paper, I've been using it for years and it's really wonderful. Being printed in red ink allows the student work to show up easily.