Linear functions
Some quantities change by the same amount at every equal step. What does that one steady rate let you say about a function, however it reaches you?
Where you are 5 inside
What this area is about
A linear function changes its output by the same amount for every equal step in its input. That steady rate means two numbers settle the whole function: the rate of change m and the initial value b = f(0), so that f(x) = mx + b. Its graph is a straight line. This area is about finding those two numbers from a table, a graph or a situation, and saying what they mean.
How these fit together
The defining test. Constant rate of change and linear tables says when a table comes from a linear function: equal input steps always give equal output steps. Linear and nonlinear functions applies that test to equations, graphs and descriptions, before plotting anything.
Reading the two numbers. Reading a linear function from its graph takes the initial value and the rate off a line and writes f(x) = mx + b. Linear functions in context builds the function from a description and names what m and b mean, with units.
Comparing. Comparing linear functions given different ways reduces a table, a graph and an equation to the same two numbers so they can be set side by side.
A path through it
Constant rate of change first, then reading a function from its graph. After that, linear versus nonlinear, functions in context and comparing across representations, with comparing last.
Finish here and you are ready for piecewise functions built from linear pieces, and for choosing a function family for data, where a line is the first family to try.