We watch fewer metrics than most companies our size. The list:
Daily active learners. Attempts per learner per day. Explain-back scores per week. Recall-review completion rate. Median Brain score movement week over week. Percentage of users whose Brain score is trending up. Free-to-paid conversion. Paid retention at 30/60/90.
We do not watch: session length (a bad proxy for learning), messages per session (rewards volume), or 'engagement' in any general sense (a metric that means everything and nothing).
Metrics shape products. We chose ours to shape the product toward learning outcomes rather than surface engagement. Every metric on this list gets worse when we ship an anti-learning feature. That is the point.
Filed by Product team on Jan 24, 2026. Under Product.