TEACHERS: register and get just 1 other colleague to join for free too, and open up the HW window: see what they set your students before you decide to set your tasks. The more teachers who join who share your students, the more powerful the tool.
SCHOOLS: With Degrumbler, you decide what year groups you want to go with. That way, you can select the appropriate teachers or groups to trial the tool with and get some traction with those teachers before upping the anti to more teachers. Teachers who are still a little uncomfortable with technology won't feel so overwhelmed if the school already has some competent and confident users who can guide and lead.