Before the first lecture, the student should have a clear idea of what a function is, and how to graph a function in x-y coordinates. For this purpose, I have selected two short videos which explain these concepts. Students with weak mathematical backgrounds should watch these videos. Students who are confident about their knowledge in these domains need not watch these introductory lectures.
A key concept is a ROOT of a function. Given y=f(x), x=r is a root of the function if f(r)=0. If we look at the graph of the function f, then a place where it crosses (or touches) the x-axis is a root of the function. In algebraic terms, a polynomial f(x) has root r if (x-r) divides the function f(x).
Graphing a Quadratic Function - 6m lecture on graphing quadratic functions
Graphing a Linear Function - Basic 5.35m lecture on graph of a linear function from Khan Academy
Functions, Rules, Tables and Graphs - Gives basic definitions and information which is required to follow the first lecture (10m)