A homeschooling practice for many is getting the student to a point where they can learn and work mostly on their own. Traditional math textbooks tend to be teacher-centric and offer little in the way of explaining concepts or how to solve problems. Purchasing the accompanying teacher's guide, if there is one, doesn't always solve this problem. Since pre-algebra is more abstract than math taught in the earlier grades, it is important that you use a curriculum that does a good job of teaching concepts. This requires good explanations to accompany good example problems for the student to work, as well as a solutions manual that demonstrates how to work each problem in the book.
Homeschooling-oriented math programs understand that there should be enough explanation of the concepts and example problems for the student to complete the lesson on their own. Since working lots of problems is the key to learning math, most homeschool math programs include lots of problems (25-35) in a lesson. The repetitive drill helps to cement the concepts and problem-solving techniques for the student.
By far the best overall pre-algebra program is Teaching Textbooks Pre-Algebra. This is designed for eight-grade students who may not be prepared for algebra and should give such a child a good foundation for attacking algebra the following year. Teaching Textbooks Pre-Algebra uses a multi-media approach including a short explanation, usually seven to ten minutes, of the lesson's concepts and sample problems. In addition there are CDs that explain the solution to every problem in the book. Test booklets and keys are included with the Teaching Textbooks Pre-Algebra package. Students love the short lessons and many become self-starters in math using this curriculum.
An excellent alternative to Teaching Textbooks Pre-Algebra is Saxon Math Algebra 1/2. In the late 1980's and early 1990's Saxon Math revolutionized math for schools and homeschools. The lessons in the student textbooks have plenty of explanation and the sample problems help the student to use the concepts before working the actual lesson. A later development that improved Saxon was the introduction of the DIVE (Digital Interactive Video Education) CDs by a third-party educator. Putting these two resources together makes for a solid pre-algebra program for any homeschool. The full Saxon Algebra 1/2 package includes the student text, tests and keys, and a solutions manual.