Weaknesses stem from the fact that there is still too much confusion about clil method.There is little information. There is much resistance to change. 

There are, then, fewer training courses for teachers willing to change. 
There is also a lack of clarity and poor dissemination of the method.

ER helps teachers to be better informed, both about their profession and about the world. This makes them more interesting to be around – and students generally like their teachers to be interesting people. For our own sanity we need to read outside the language teaching ghetto. For the sake of our students too.

It also helps teachers to keep their own use of English fresh. 

I experienced the benefits of extensive reading in a class where I was a support teacher. It gave an immense boost to my vocabulary and broadened my outlook. Unfortunately, I don’t read fiction much these days and I feel its negative impact on my vocabulary and the need to read more. Students learn the language not only from books, but from their teachers where the exposure to the language is great. They remember the words they pich up from their teachers much better than the words they are forced to learn which another advantage of extensive reading.

I think that is hardly find a modern novel which is provided with different interesting activities and which might help you to get feedback from your students and keep up their interest throughout the reading course.