#myfavfriday Slope Formula
I'll go ahead and warn you that this won't be the best explanation.
I'm posting about a different way (for me) of teaching the slope formula. I transition from functions to linear functions via tables. As we learn to use a function rule to create a table, we then plot the points in the table and graph.
After we are experienced with that, I teach about slope (I should blog about that too I suppose) in context and we start counting rate of change and slope.
Once we're familiar with that concept, I take students back to tables and show them how to find the slope from a table. For the first time, I translated that to ordered pairs. When I give the student's ordered pairs, they write them in a table (t-chart) and subtract to find the slope.
Here's an example:
I like this way better because there isn't as much confusion in finding x1 and y1. It doesn't matter which ordered pair you write first anyway.
Sometimes the students do write the pairs vertically instead of horizontally but overall I am much more satisfied with this method rather than the formula.
As much as I can, I am trying to get away from memorizing formulas and trying to build things conceptually. Now you may say that students have to memorize this method as well but I would respond to that that the tables are much more of a natural progression than a random formula.
Na na boo boo.