This explains in detail Quadratic Interpolation using an example given by a student. The problem is explained in general terms so students can apply it to a variety of polynomials.
Dr. Math


Another detailed explanation of Lagrange Interpolation based on example from Dr. Math.
Dr. Math

This link gives a detailed description on Lagrange interpolation and how to go about using it. It also provides links to other areas of Dr. Math that can help with interpolation.
Dr. Math

Gives a detailed explanation on working with Linear Interpolation.
Math Pages

Gives an overview on working with cubic spline interpolation
utah.edu

Gives a definition for three different kinds of interpolation: Polynomial, Rational Function, and Cubic Spline.
Efunda
