AAA Math
Aaa Math: Inverse Relationship of Addition & Subtraction
There is a great interactive problem set for students to practice the concept of the inverse property. This would be a great review before a unit on solving basic equations.
Interactive Mathematics
Interactive Mathematics: Addition & Subtraction of Fractions
The addition and subtraction of algebraic expressions is presented with detailed examples and exercises for extra practice.
OnlineMathLearning.com
Online Math Learning: Adding & Subtracting Positive & Negative Decimals
An interactive worksheet for practice in the addition and subtraction of decimals with positive and negative signs.
Cool Math
Coolmath: Adding & Subtracting Polynomials
This prealgebra lesson explains how to add and subtract polynomials.
National Council of Teachers of Mathematics
The Math Forum: K 12 Math Problems, Puzzles, Tips & Tricks
At this site us these tips & tricks to help students become better mental mathematicians.
Other
Mathpower: Elementary Algebra Assignments
Test your algebra aptitude at this colorful website filled with algebra assignments for upper elementary and middle school students. Assignments explore algebra concepts using addition, subtraction, multiplication, fractions, division,...
Purple Math
Purplemath: Adding & Subtracting Rational Expressions: Introduction
Finding common denominators is no problem with Purplemath. Use this lesson to learn how to add and subtract rational expressions with these great examples.
DLTK
Kidzone: Math Worksheets
This site provides printable worksheets for basic math operations. Organized by grade level, concept & theme.
Math Cats
Math Cat: Fact Family Card
Everything you need to know about fact families can be found here. Discover what fact families are and learn different strategies for using them. Links included to print your own fact family cards, create a fact family house, and play a...