I used to have kids create the graphs with pencil and paper then look for patterns but that was 20+ years ago. Last year I used GeoGebra and a Java Applet for an exploration of slope. Get the students to play with y=mx+b and build their own understanding.
So far this year I am really impressed with Desmos. A real great tool to build an exploration around.
To see what I mean check this out.
