I use a collection of books and have good reasons for doing so. I hope.
Superkids books 1 and 2 for the beginning classes. That is grades one and two students. These books provide useful accelerated vocabulary and are listening and speaking based. That means the students are not buried in writing from the beginning as is the case with Let’s Go. I run a parellel phonics and grammar program that introduces graded writing and reading skills.
I then switch to Let’s Go at book 3. It has a solid grammatical foundation and makes an easy transition into the basic writing skills. I continue to run a seperate grammar program and phonics program with additional reading. I stick with Let’s Go to book 5. However, Let’s Go is very weak on vocabulary and reading development so I add through the reading program a lot of new vocab.
After Let’s Go 5 I switch to Beeline 4. Beeline is designed for learners outside Asia. It is a good series but it overloads Taiwanese learners that don’t have a strong foundation and a lot of English input. However, by this stage I think the students are more than ready for it and they breeze through the activities. I then complete the Beeline series all the time running my own seperate reading and grammar program. By this stage the grammar program has morphed into a writing program.
Ultimately at the end of all this I focus on writing. After years of speaking in the classroom the students are usually proficent speakers, their listening skills are fine and their reading skills are very high. In addition, as writing, for most students, is likely to be the most important skill they will ever need to master in English and because preperation for writing assignments involes the other three skills anyway, this is what I focus the higher level students on. Of course when you teach writing, there is no limit.