Hi, I'm the author of Learning Mathematics with the Abacus (check out the website at http://www.mathabacus.com ). It's a book that teaches kids the basic method of using the abacus as a calculation tool in their math classes to develop their mental arithmetic skills.
Hope you guys can take a look and see the lesson plan outlined in the book. There is the textbook and the activity book. It's now being used in many schools throughout Malaysia, endorsed by the Ministry of Education, Malaysia.