Here is an interesting and informative website:
Blended learning in ESL gives your students a chance to take responsibility for their learning. Becoming self-motivated, autonomous learners is a good habit for all students to get into. By giving students asynchronous tasks to complete outside of regular class time, allows the student to take control of a portion of their learning.
What Is Blended Learning in ESL and How Can I Implement It ...
bridge.edu/tefl/blog/blended-learning-esl/