... proportions and constant of proportionality, understanding slope of a line... linear and quadratic equations... motion problems (edinformatics.com)
@BauerOutage oh and also do you understand the slope of a line and y intercept? (sbnation.com)
Modern researchers have used more sophisticated techniques to identify problems with the Friedman Curve, generally about the slope of the line which represents the speed or progress of (birthingnaturally.net)