The video at the bottom of the page demonstrates one example of how to have a high-level online discussion that leverages a pedagogical approach.  In this case, we use Problem Based Learning to help students focus on a structured problem and then layer in academic language as you talk about possible solutions.  The website I used is Dan Meyer's Three Act Math. 

Suggestions to amp up your online discussions:

1) Search Google for a content-specific video with a problem to be solved.

2) Post a problem related to the video to a place where students can reply to the problem after watching the video.

3) Have students perform educated guesses (as is illustrated in the video).

4) Guide discussion with high Bloom's question stems.

5) "Reveal" the answer(s) after all students have contributed.

In the classroom, you would use WAIT TIME as a way to allow students of different thinking levels to process.  In a discussion post like this, you might open the discussion one day and allow for thinking time by making it due the next day.

You DO NOT have to use Problem Based Learning as your learning vehicle.  But please do use student's natural curiosity, use problems to create curiosity, and allow for wait time.