I have been extremely impressed with the free ciriculum and environment at https://code.org/ . It has lots of child friendly skinning and bite-sized "puzzles" that teach you step by step but build real understanding of more complicated ideas. I have "assisted" mainly watched and answered occasional questions with a bight 7 year old who has completed Course 3, which uses a scratch like visual block programming enviroment.

There is a more advanced class that teaches javascript.