Teri Coppedge teaches Spanish using TPRS methodology (TPRS = Teaching Proficiency through Reading and Storytelling) in Ashland, Oregon. Posts from her current and previous classes appear here, as well as information on how to take lively Spanish lessons in Ashland, Oregon, as part of OLLI at Southern Oregon University.
Here's a very very brief look at someprominent theories of language learningand development. There are links to each one, as well. FluentU has lots of useful videos, lessons and other aids to language learning.