What the activity asked
The activity asked us to take a unit we had taught or expected to teach and rebuild it using backward design: start from what students should be able to do, decide what evidence would demonstrate it, and only then choose the activities. I used the loops-and-iteration unit from Introduction to Computer Science I.
What I made
A three-week unit plan with four learning objectives, each paired with the specific evidence that would count as meeting it, and a mapping from every class activity to the objective it serves. The most useful column turned out to be the one I added: for each objective, the misconception I expected students to arrive with.
What I learned
Rebuilding the unit backward exposed how much of my original version existed because it was the order the textbook used. Two activities I liked served no objective I could name, and one objective, reasoning about loop termination, had no assessment attached to it at all, which explained a pattern of exam answers I had found puzzling at the time.
How this shapes my teaching
I now write the assessment before the lecture, not after. It is a small change in sequence that makes it much harder to teach something I have no way of knowing whether students learned. It also gives me a concrete answer when a student asks why we are doing an activity.