RYUN Engineering & Research
Blog & Engineering Notes
Things we built, measured, or got wrong. Written by the developer, dated, and updated in place when code or benchmarks change.
Articles (1)
#FrenchΒ·11 min
The i+1 Comprehensible Input Formula: How to Measure Video Transcript Difficulty Across CEFR Levels
Stephen Krashen's i+1 hypothesis requires 95% to 98% lexical coverage for natural language acquisition. Discover how to check the CEFR difficulty of foreign YouTube transcripts across Spanish, German, and French using lexical density and distribution curves before watching.
Nov 7, 2026Read