Hi Dreyfus, this site has over 3000 idioms and explanations English Idioms and Idiomatic Expressions A reference of 3520 English idioms and idiomatic expressions with definitions. Idiom Categories - Search - English Idioms Beginning With 'A' - A little bird told me www.usingenglish.com/reference/idioms/

I don't get what you mean by teaching them? You want to know methods to teach idioms or just a list of idioms ,that you could teach to your students?