We started our homeschool math curriculum with Teaching Textbooks and have not felt much need to move to another program. We have added Life of Fred to our math line-up, but our daily work is done on Teaching Textbooks. Both of my students started at Level 4 when they were ready for a more formal math program. There is a placement test on the Teaching Textbook site.
Lessons begin with an audio lecture and step-by-step instructions shown on screen for the student to follow. This is great for me as everything is taught and there is no instruction needed from me. Then the student is given a few practice problems to see if they understand the day’s lesson before they move on to the actual problems of the lesson. If a student misses a problem they are presented with the option to keep going or view the solution and step-by-step instructions are given. There are regularly scheduled quizzes built right into the lesson line-up, so there’s no extra work for me. All of this is kept in a grade book within the program. You can also generate reports and view if the student has viewed the solutions to problems that they missed. In newer versions of the software you can have more than one student in the same level at the same time.
You can also get the printed textbook for those students who need the extra practice or who don’t want to be in front of a computer. We have opted not to get the printed textbook after the first year. I supplement extra practice with online games or printed worksheets.