English Class

I have an English class that I teach every Friday and one that I teach every Saturday. To be honest, I really have no idea what I am doing. Although everyone seems to enjoy it, sometimes I panic when I do not know the answer to a question. (Is this an Adverb? An Adjective? Why is it "does" and not "Is"? Etc) My class on Friday is of a much higher level than the class on Saturday. I thought that maybe if I went really slow and explained all the sentences and the structure as best that I could that I could start them off on something easy (Like a small news article) but relatively intermediate in terms of level.

I was wrong.

It is difficult because the range of levels in Saturday's class is so great that if I did something at the beginner level, some of the students would find it too easy. But as I explained above, if I did something of a higher level it will end up being too difficult.

The class has 18 students. There are 4 men and of those four I would peg three of them as intermediate. The rest of the class is in early beginner. Also female.

The old English teacher (Who I have never met and do not know anything about besides that his name was Joshua) gave them crossword puzzles and word searches as homework. But I have been told by a few that they disliked having to do that very much. ... But 1/4 of them really enjoyed it.

It would be nice to work with a company that had a book with set lessons and such. As it is, finding and making my own is proving to be difficult and moreso as time goes on.

So what I have been thinking and researching is if I couldn't buy some English teaching books online that have set lessons in them. That would make things easier for me but now the question is... which books would be the best to buy?