If you are not confident in math but he is confident, you can try AOPS. They seem to split normal algebra 1 into algebra 1 and 2 so you'd need both courses to equal what school covers. We used it as a supplement to Thinkwell Algebra 1 which was what we needed because my child was not ready to type in LaTex and have instruction only once per week in their class.
I emailed talked with the APos people. When I emailed to ask what book to help my son who is in Algebra II. Their Algebra I book is actually what is normally two classes, Algebra I and 3/4 quarters of Algebra II. (No trig. in APos Algebra I) As I have the book & my son's Algebra II book, I can confirm that this is correct.
