Discovery Education
Discovery Education: Web Math: How to Subtract Two Numbers
WebMath offers a good practice site for basic subtraction. Children can type in the problem and an answer is given with explanation. A good site to check homework problems.
NumberNut
Number Nut: Subtraction Overview
Get an overview of the subtraction process in this brief lesson that introduces key concepts, vocabulary, and symbols. Links to related, interactive practice are also available in this lesson.