distinguish between proportional and non-proportional situations using tables, graphs, and equations in the form y = kx or y = mx + b, where b does not equal 0

What is a Linear Function?
What Does Direct Variation Look Like on a Graph?

Want to know what a direct variation looks like graphically? Basically, it's a straight line that goes through the origin. To get a better picture, check out this tutorial!
What's a Function?

You can't go through algebra without learning about functions. This tutorial shows you a great approach to thinking about functions! Learn the definition of a function and see the different ways functions can be represented. Take a look!