Lessons that open in 15 seconds, not 40
Lessons are the third most-visited feature in Zero Gravity's study app. A student picks a topic and an AI writes them a lesson on it: a few short sections to read, then a quiz.
I took the first version, which was reading material and a quiz block behind a shimmering loading page, and reworked it: a better model, a warm-up question for the wait, check-ins that make sure each section lands, and pictures that are accurate and don't hold anyone up.
TL;DR
The first lesson was reading material and a quiz. Students watched a shimmer while it was written, and when it arrived nothing asked whether any of it had gone in. For one of the most-used features in the app, it was the least finished.
I moved lesson writing to Sonnet 5.5, which wrote faster, cost less and won every blind comparison. A lesson with no picture now opens in about 15 seconds, where it took about 40. A picture painted from scratch holds that to about 38; one that's already in the library, or was painted for another lesson, brings it back to about 21. I gave the wait a job, a short exam-style question marked again at the end, and added check-ins that make sure each section is read, and that also hide the pictures still painting behind them.
The problem
The first lesson was reading material and a quiz. Students watched a shimmering page while it was written, which took about 46 seconds, and when it arrived nothing asked whether any of it had gone in. It's the third most-visited feature in the app, so a lot of students felt that.