Last year I had a lot of success with students designing their own tasks. From a display point of view it yielded a lot of interesting Rational Functions and Trig Graphs. However, from time to time the desire for open design caused issues. As an introduction for trig, I want to demonstrate that side ratios in 30/45/60 triangles are universal regardless of size. Last year I had students create 9 triangles, 3 of each type. It's one of many Right Triangle things.
This process took about a thousand times longer than I anticipated. And in one class a bunch of kids missed out on the payoff (O/H and A/H have the same value regardless of size) because they hadn't gotten around to figuring out the ratios.
Other instances of this came up and I made a tweet I can't find where I came to the conclusion that the time required for a task is [a lot].
Did myself a favor and preloaded the triangles.
A bit of a "duh" moment, but you have to learn these lessons some times. Discovery activities really only work when everyone has a chance to make the discovery.