constant of proportionality	the constant in a proportional function equation; it describes the ratio or proportional relationship of the independent and dependent variables—also called the constant of variation or the rate of change
constant of variation	the constant in a proportional function equation; it describes the ratio or proportional relationship of the independent and dependent variables—also called the rate of change or the constant of proportionality
dependent variable	a value or variable that depends upon the independent value
function	a kind of relation in which one variable uniquely determines the value of another variable
independent variable	a value or variable that changes or can be manipulated by circumstances
input	the independent variable of a function—input determines output
output	the dependent variable of a function—output is determined by input
proportional function	a function in which the input times a constant equals the output
rate of change	the constant in a proportional function equation; it describes the ratio or proportional relationship of the independent and dependent variables—also called the constant of variation or the constant of proportionality
relation	the relationship between variables that change together