Sprachbau
The method behind Sprachbau
Sprachbau isn't a vocabulary drill with a coat of paint. Every feature exists because the research on second-language acquisition points to it. Here's what we build on.
Comprehensible input (~95% known)
You acquire language by understanding messages slightly beyond your current level — Krashen's "i+1." Sprachbau generates content at your exact frontier: sentences built almost entirely from words you already know, introducing only two to four new items per session. Too easy and you learn nothing; too hard and you stall. We aim for the narrow band in between, automatically.
Spaced retrieval with FSRS
Memory is strengthened by retrieving information just as you're about to forget it. Sprachbau uses FSRS-6 — a modern, data-driven scheduler that predicts your recall probability and targets 90% retention — rather than the decades-old SM-2. Crucially, cards are sentences with a blank, not isolated word pairs, so you always retrieve meaning in context.
Pushed output with corrective feedback
Understanding isn't enough; producing language forces deeper processing. Sprachbau asks you to write, then grades it — separating structure errors (grammar and construction worth drilling) from surface errors (typos and slips). The structural mistakes you make become targeted practice cards, closing the loop between grading and scheduling.
No gamification
Streaks, points, and badges optimize for daily active users, not for learning. Sprachbau deliberately has none of them. The only metric that matters is whether you understand and produce more of the language than you did last week.