Great article on How to Create Great Teachers. It's focused on K-12 education primarily, but there is wisdom in the discussion relevant to workplace learning.
Here's the major points I take away:
- Great teachers need deep content knowledge.
- Great teachers need good classroom-management verbalization skills.
- Great teachers need their content knowledge to be fluently available to them in the context of typical classroom situations. To get this fluency, they need to practice in such situations---and practice linking actions (especially their verbal utterances) to specific classroom situations.