I would also recommend the Amsco First Year Workbook, as it is a strong grammar source. It would have to be supplemented with vocabulary. I have used a workbook called "Spanish is Fun" in the past. It is a great source of both grammar and vocabulary, like a textbook, but in soft cover form. It is better suited to a younger student, though. I do not have a copy at home, so I am not sure if it is published by Amsco.
Good luck.
Jeanne F. Clawson
French teacher
Port Charlotte H.S.
Port Charlotte, Fl