I think reading books is great way of extending your vocabulary. It would be the best if the Ss made lists of words they did not know and wanted to learn.
It would be even better if the teacher gave Ss an opportuniny to share their opinion on the book and the new words they have learned with their classmates.
I think that it is a very nice idea, because Ss can find many unknown words in books. Also, it is important to motivate them for reading. The opportunity to share their opinion on the book, ... would be great. To be honest, I am not sure, whether Ss would really read the books without a "requirement" to share it. But it is the same in each of our activity, we have to motivate our Ss and believe, that they would try our ideas :).
I agree that reading a book is a great way of learning new vocabulary, especially when children can choose a book they like.
There might be a problem with choosing an appropriate book that wouldn't be too difficult- mainly for begginers. I remember that my cousin used to read english books at school which were made specifically for young english learners. There was a vocabulary list at the end of every chapter so when they did not understand they could have looked at this list. So I think this could work very well for children at primary school. :)
I totally agree with girls, it is awesome way to learn new vocabulary and also motivation for reading in general. The problem with inappropriate books may be solved by providing Ss the list of books? (Large of course, so everyone is able to find something s/he wants to read - as in our Czech literature :))
Yes, we should not underestimate the power of books! :D
And it is a great idea to give Ss a place and time to share their thoughts about the story. This way they will probably bring more new words and they will learn how to formulate their opinions (which is a very valuable skill).
I agree that reading books can extend your vocabulary a lot especially if you write down the words you did not know before.
It is much easier to learn a vocabulary that is somehow familiar to you than words you have never heard of.