proportional relationships – the relationship among a group of ratios that are equivalent.

constant of proportionality – the unit rate in a proportional relationship.

coordinate plane – a two-dimensional space formed by two perpendicular number lines called axes.

ordered pair – a pair of numbers (x, y) that describes the location of a point on a coordinate plane.

origin – the point (0,0) where the x-axis and y-axis intersect on a coordinate plane.

Lesson 10 Vocabulary