Math Is Fun
Math Is Fun: The Evolution of Numbers
Discusses what numbers are and how our understanding of them has evolved over thousands of years, from simple counting to negative numbers and irrational numbers, for example. Includes a set of practice questions where students identify...
Interactive Mathematics
Interactive Mathematics: Complex Numbers: Basic Definitions
After reviewing the process of solving quadratic and cubic equations, a definition of an imaginary number is given. Also included is a demonstration of simplifying powers of the imaginary number and writing complex numbers. Examples are...
Friesian School
Friesian.com: Imaginary Numbers
This site from Friesian.com contains a detailed definition of imaginary numbers along with a few examples.
University of Toronto (Canada)
University of Toronto: Imaginary Numbers in Real World
This site from the University of Toronto contains revelant information regarding imaginary number appliances to the real world.
Purple Math
Purplemath: Complex Numbers: Introduction
This website provides an in-depth lesson on complex numbers. You learn about simplifying, adding, and multiplying complex numbers by viewing example problems that are worked through step-by-step. Continue on to pages 2 and 3 which...
University College London
University College London: Complex Numbers: Real and Imaginary Parts
Contains a brief summary about the real and imaginary parts of complex numbers.
Clark University
Clark University: Dave's Short Trig Course: Complex Numbers
This site from a professor at Clark University teaches you about complex numbers.
Cut the Knot
Cut the Knot!: What Is a Number?
Casual and clear but definitely upper-level discussion of rational, real, imaginary, and several other types of numbers. Links to related sites.
CK-12 Foundation
Ck 12: 1.5 From Quadratics to Complex Numbers
This section introduces imaginary and complex numbers in the context of solutions to quadratic equations that don't have real-number solutions.
CK-12 Foundation
Ck 12: Algebra Ii: 1.6 the Complex Plane
This section includes operations with imaginary and complex numbers and plotting numbers on the complex plane.
Math Medics
S.o.s. Math: The Complex Plane
Contains a lesson and practice exercises about complex numbers in a complex plane.
Khan Academy
Khan Academy: Multiply Complex Numbers (Basic)
Multiply complex numbers by single terms that are either real or imaginary. Students receive immediate feedback and have the opportunity to try questions repeatedly or receive hints.