I �d like to know some convenient methods for teaching very large classes that only have a book and a board as teaching aids beside the teacher.. 

do you have any idea????

I have a large number of classes and have been trying to make my classes enjoyable and fun and also take control of the discipline

Some ideas about my rewarding system I have posted here and all of them on my blog http://lusine13.blogspot.com/search/label/CLASSROOM%20MANAGEMENT

What about games I usually divide the class into teams according to the rows and hold competitions on the board ,we do many exercises on the board,each time a student from the team comesand does the exercise,if that �s correct the team gains a point or a star.The team that gets the most points/stars is the winner.

I also use flashcards a lot and do many activities with them:GUESSING GAME:a student is shuffling the flashcards until the class says STOP then they give questions and guess what he/she �s holding or MEMORY GAME:I distribute the flashcards among the students randomly,then say the name of the flashcard and the come to the board,then they turn the flashcards and the students should say what flashcard they �re holding.

Hope these activities can be useful for you.

Good luck