Great question! I totally cringed while reading the dialog piece Hoffer writes about on page 68-69. I have heard those exact snippets in my room and just couldn't figure out how to stop it!
Last summer I learned about the "flipped classroom", layered curriculum, and interactive notebooks. So I recorded a bunch of lessons, created menus of activities and planned out the notebooks. My vision for my class would be that they watch the video and start their notes for homework, then the first 10 minutes of class would be small group discussion before moving on to the activities. Things started off okay, but did eventually break down over the course of the year and after reading this chapter I feel that it was because I never taught them how to have those discussions. I fell into the trap of "if you put them in a group and tell them to talk about math...they will!" Nooooooo preteens-teenagers do not work that way!
Again, this is another chapter I am going to wear the crap out of while lesson planning! Not only does Hoffer give detailed outlines for scaffolding and structures (p.80), she also explains how to keep students accountable and how to observe them in their discussions!