1. Make sense of problems and persevere in solving them. 2. Look for and express regularity in repeated reasoning. 3. Use similar triangles to explain why the slope m is the same between any two distinct points on a non-vertical line in the coordinate plane; derive the equation y = mx for a line through the origin and the equation y = mx + b for a line intercepting the vertical axis at b. 4. Solve linear equations with rational number coefficients, including equations whose solutions require expanding expressions using the distributive property and collecting like terms. 5. Interpret the equation y = mx + b as defining a linear function, whose graph is a straight line; give examples of functions that are not linear.