Although I made the quizzes some time ago for my C1 students, I still find Riddle a very good tool for teachers. A pity they do not let you edit the quizzes you made in the past any more.
Visit my advanced website if you want to test your knowledge on idioms in English. You will also find a link to Cristina Cabal´s blog with another quiz on idioms as well.

If you want to learn more about English and idioms BBC Podcasts the English we speak offers a ginormous and mindblowing quantity of podcasts with all the trimmings, more than 200 on the topic. Don't get me wrong,  but I suppose you'd rather paint the town red or get some nosh. In any case,  try not to beat around the bush and sleep on it!

This is a Cambridge audio listening drama with activities for levels B1-B2. 7 episodes:

Extra is a video course to learn English. Find all the episodes with subtitles on Youtube and all the activities with short grammar notes on planet-schule

To download this striking and significant BBC podcasts series go to BBC Podcasts Downloads

Well, 86% of people are mistaken about this. If you want to know why, visit BBC iwonder to discover. You will be able to watch a video, download the transcript and what is more important, find out your real star sign.

The newest religion. Did you know about it? Learn about this parody religion (according to media) and pastafarians (their followers)  watching this video

You can also download their bible (pdf file): The Gospel of the flying Spaghetti Monster written by Bobby Henderson in 2006. For more information visit The European Church of the Flying Spaghetti Monster

Edmodo is a huge community that allows teachers and students to be connected. I created an account that I will use with my high level groups:  https://www.edmodo.com/joepinetreebush

LearnEnglish Grammar by British Council 
Improve your grammar skills with various grammar topics and activities designed for different  levels.

LearnEnglish Elementary Podcasts by British Council
Each podcast is a 20min long story. English subtitles help you to understand the audio better, so you can answer their questions.

101 Tips for IELTS Speaking
Many tips to improve grammar, fluency and vocabulary.

Advanced English & Thesaurus
Not an ordinary dictionary, grouping nouns, verbs, adjectives and adverbs into sets and also shows you how different words link to each other in terms of synonyms or opposites.

Gobby
This app teaches you catchy phrases that English Native Speakers use.