Online courses in EdX that are appropriate for middle school teachers:
CS for All: Intro to CS and Python from Harvey Mudd College – https://www.edx.org/course/cs-all-introduction-computer-science-harveymuddx-cs005x-0 Launches in June 2016.
Harvard’s Intro to Computer Science https://www.edx.org/course/introduction-computer-science-harvardx-cs50x Self-paced and very highly rated
The Beauty and Joy of Computing from Berkeley https://www.edx.org/course/beauty-joy-computing-cs-principles-part-uc-berkeleyx-bjc-1x. This course was launched last fall but can be accessed as an archived course now. It is based on the CS Principles course taught at Berkeley.
MyCS: Computer Science for Beginners https://www.edx.org/course/mycs-computer-science-beginners-harveymuddx-cs001x. Also a Harvey Mudd course directed specifically to middle school teachers. Launched last fall but now available as an archive.