CK-12 Foundation
Ck 12: Algebra: Factorization Using Difference of Squares
[Free Registration/Login may be required to access all resource tools.] Factor the difference of two squares and perfect square trinomials and solve quadratic polynomial equations by factoring.
Quia
Quia: Square Roots (Concentration Game)
This concentration game explores square roots. There is a link to a list of the numbers being used so students can check their answers.
CK-12 Foundation
Ck 12: Algebra: Properties of Rational Numbers
[Free Registration/Login may be required to access all resource tools.] Recognize and identify irrational numbers and the set of real 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.
University of Saskatchewan (Canada)
University of Saskatchewan: Factoring Polynomials
This site from the University of Saskatchewan provides an explanation of factoring by grouping, greatest common factor, perfect squares, and difference of squares. Higher degree polynomials factored as well. Some examples provided along...
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Square Roots and Irrational Numbers
Math Forum response to whether square roots of all non-perfect squares are irrational. Contains a proof showing that such cases are, indeed, irrational.
Alabama Learning Exchange
Alex: What's My Number
In this lesson, eighth grade middle schoolers will learn the steps necessary to approximate the square roots of numbers that are not perfect squares. Students will use a number line as a visual aid to complete this task.
Help Algebra
Help algebra.com: Factoring Polynomials
Several types of factoring are covered in this article, including common factors, grouping, special factors, and completing the square. The examples include detailed explanations of the factoring process.
Sophia Learning
Sophia: Introduction to Roots and Radicals
Sophia: Introduction to Roots and Radicals uses teacher tutorials and online assessments to introduce and analyze concepts such as Even Roots, Negative Numbers, Odd Roots, Partial Root, Perferct Squares, Radicals Root, and Roots.