I love this question! It really speaks to our desire to find the "magic bullet", the "one answer" that is going to miraculously make all our students learn everything they possibly can!
Interestingly, this very question is at the core of a number of studies completed by various researchers in the field of education. And, over and over again, these researchers found that the single most important school-related factor influencing student achievement is in fact
No single instructional strategy was found to be "better" or more effective than another in determining student success, but rather, the soft skills of the teacher, the rapport he or she consciously developed with students, and his/her committment to continuous improvement as an educator, was what made the different in the vast majority of the research studies.
That's a lot of pressure on teachers!
On the other hand, it is also a promising proposition: No matter the educational or life background of you or your students, you have the potential to greatly impact the success of your learners.
An authentic teacher who is deeply committed to the students he serves will succeed in his endeavors. The data says so!