Purplemath
http://www.purplemath.com/
Algebra Lessons

Pre-Algebra Activities
http://www.k111.k12.il.us/king/math.htm#PreAlgebra

National Library of Math Manipulatives- Data Analysis & Probablility
http://nlvm.usu.edu/en/nav/topic_t_5.html
Virtual manipulatives related to the NCTM Data Analysis & Probability standard.

National Library of Math Manipulatives- Algebra
http://nlvm.usu.edu/en/nav/topic_t_2.html
Virtual manipulatives related to the NCTM Algebra standard.

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Purplemath
http://www.purplemath.com/
Algebra Lessons

CoolMath.com - Algebra I Lessons
http://www.coolmath.com/algebra/Algebra1/index.html
Contains lessons on Polynomials, Exponents & Radicals, Solving Equations, Inequalities, Lines, Systems of Equations (2x2's),  Factoring & Dividing Polynomials,  Quadratics (Solving and Graphing,) Complex Numbers,  Algebraic Fractions (Rational Functions), &  Functions.

Algebra Activities
http://www.k111.k12.il.us/king/math.htm#PreAlgebra

National Library of Math Manipulatives- Algebra
http://nlvm.usu.edu/en/nav/topic_t_2.html
Virtual manipulatives related to the NCTM Algebra standard.

CoolMath.com - Algebra II Lessons
http://www.coolmath.com/algebra/Algebra2/index.html
Contains lessons on Equations, Fractions & Decimals, Intervals, Inequalities, Lines, Domain & Range, and Exponents & Radicals.

National Library of Math Manipulatives- Algebra
http://nlvm.usu.edu/en/nav/topic_t_2.html
Virtual manipulatives related to the NCTM Algebra standard.

Geometry/ Area / Perimeter
http://www.k111.k12.il.us/king/math.htm#Geometry/
Information on General Geometrical Terms, Polygons/ Shapes /Nets, Angles, Area/ Perimeter, Symmetry/ Rotations/ Reflections/ Transformations, and Tessellations.

National Library of Math Manipulatives- Geometry
http://nlvm.usu.edu/en/nav/topic_t_3.html
Virtual manipulatives related to the NCTM Geometry standard.