Khan Academy
Khan Academy: Features of Quadratic Functions: Strategy
Identify the form of a quadratic function that immediately reveals a given feature of that function. Features in question are the y-intercept of the graph, the zeroes ('roots') of the function, and the vertex of the parabola.
Purple Math
Purplemath: Graphing General Polynomials, Radicals, Rationals, and Piecewise Fun
This resource provides an overview of graphing, giving examples of general polynomial, radical, rational, and piecewise functions. Also includes advice on common mistakes made by students.