I read Glen’s post Writing Linear Equations about a month ago. I remember thinking… hmmm. really? but a line doesn’t have a vertex, does it? is that legal? can I do that? Will it always work? So I tried some. Several. It made perfect sense.
Please take a moment to read his post…
Anyway, I reread within the week and wondered if I should give it a try – I mean, it did make sense. A lot of sense. But I was afraid it would confuse the students, I was afraid to step out on the limb. I wasn’t sure how to introduce it.
After seeing a tweet from @druinok, I decided to give it a try. I shared the form y=a(x-h)+k and asked the students if they had ever seen it before? In the functions unit – transforming functions (focus on quadratics, absolute values and radicals/square roots) – they were familiar. I graphed a line with a given slope, then translated it (a point marked at then origin) the given point (h, k) – to begin as a visual.
Anyway, within 3 examples – EVERY single student was doing it – writing equations of lines…CORRECTLY! yes. Thank you Glenn & Druinok!
In my geometry classes, I still had a handful of students struggling with this “algebra 1” skill. I pulled them off one-on-one and simply said, lets try it this way, explaining the vertex form. They are all running with writing equations of lines now~ AWESOME! I am a believer in vertex form of a line. Give it a try. Go ahead don’t be afraid. It works, beautifully.