"y = mx + b" and teaching

I've been trying to brush up on some algebra from years past. It's amazing, the little things you forget when you don't use them on a daily basis. For example, the equation to determine the slope of a line? I remembered y = mx + b, but that doesn't necessarily help, especially if you don't know what in the world b is. (The y-intercept...where a line crosses the y axis.) Suddenly, upon hearing "rise over run," it all came back. It would be amusing to be a tutor for algebra and not know basics like this. Then again, who knows? Students might actually benefit from having to explain things to me. Teaching a topic really requires that you know exactly what you're talking about.