Plan Explain Mistakes

Plan: explain the mistake on a wrong grammar answer

Source of truth: this wiki page.

Written 2026-10-05. The owner called this very important.

What the owner asked

Explain my mistake (Duolingo): show the relevant rule on a wrong answer: for grammar questions. this is very important

What exists

• Grammar tables: 80 tables, 2,497 cells. Each table has one general note, such as the present's "the verb's stem, then -ता, -ती or -ते for the doer's gender and number…". It shows after any answer, right or wrong, beside the table.
• Grammar sentences: 1,021 cards, 767 with a note of their own, such as "पी is feminine because चाय is, whoever drank it." The note shows after any answer in the typed and choice drills.
• The word-order drill shows no note at all.
• Nothing ties a wrong answer to its rule. The learner gets the answer and the general note, never what went wrong in what they wrote.

What it takes

1. Read the mistake from the table, with no new content:

   • a wrong answer that is the form of another cell of the same table says which. For example: "That is the form for तुम. For मैं, जाना is जाता हूँ." Then it gives the rule that tells them apart;
   • a wrong answer that is the word uninflected says that it is the dictionary form, and what it needs.

   This covers all 2,497 cells.

2. Rules a card can name:

   • a grammar deck lists its rules, each with a permanent id and a short text;
   • a table cell or a sentence names the rules it tests;
   • a wrong answer shows those rules first, and the deck's general note after.

   This changes the deck format, which needs the owner's answer (AGENTS.md).

3. Known mistakes, written for each sentence: common wrong answers, each with why it is wrong. For hi-0480: पिया, "चाय is feminine, so पी". They double as the extra tiles of the word-order plan (word-order-tiles.md), so each extra tile explains itself when it is used.

4. Everywhere a grammar answer is wrong: typed, chosen, in word order and spoken. After a right answer, the note stays as it is today.

5. Content:

   • rules for the 80 tables;
   • rules named on the 1,021 sentences, from the 767 notes that exist, with the rest written;
   • known mistakes for the sentences, by agents, marked for review.

6. Tests for every kind of mistake read from a table, rules shown before the note, known mistakes, and each drill.

To decide

• The field names for rules and known mistakes.
• Whether the rules are written in the learner's language, as facts are (en, bn, hi), or in English first.

Estimate

Part	Hours
Reading the mistake from the table	3–4
Rules and known mistakes in the format, the validator and every drill	4–6
Content: rules and known mistakes, about 1–2 hours per language	8–16

Confidence: medium. Because the owner called it very important, it could come early in the schedule, right after the deck downloads.

See also: Roadmap · Plans-Index · Home