Explanation
Why languages are a budget of hours, not a lesson plan
A minority language survives on input hours from several speakers. Yearkeep plans and counts the share of waking time per language instead of teaching.
Yearkeep does not teach the child a language. It measures and plans the hours the adults give each language, because that is what the evidence says matters.
The evidence in three lines#
- Vocabulary in each language tracks the share of input in that language (Place and Hoff, 2011, with two-year-olds).
- Hearing a language from several native speakers helps beyond the raw hours.
- Below roughly a fifth of waking input, a language is heard but rarely becomes productive.
What follows for the product#
Percentages, not lessons. The plan holds a target share per language for the child's age band, summing to 100. The default over-weights the language with the least support outside the home, because that is the one that fails first.
Every block carries a language. Once each block has a language, the planned split for the week is arithmetic, and the week view can warn before Monday. The actual split comes from logged blocks, so the dashboard shows what the adults really gave.
Adults are speakers. Each adult has a language. Every other adult speaks their strongest language. Grandparents on calls are scheduled as blocks, because a language with only one speaker is fragile.
Estimates, honestly. The dashboard says "estimates, not precision" and shows weekly trends. Minutes are logged block minutes times the block's language share, not a microphone.
Floors, not perfection. Any planned language under 15 percent turns red. Under target minus five points turns amber. A language under 15 percent for eight straight weeks, or no new words for six, becomes a calm monthly check, never a grade.
Words, separately. Quotes are logged in their own script. New words go to an inbox a parent approves, so the vocabulary counts mean something.
What it deliberately does not do#
It does not put the child in front of a language app, does not drill, and does not promise fluency from a weekly class. The Mandarin decision in settings is explicit about that: defer, plan for age four with real immersion, or skip.