For teachers: tracking 20 students' mistake types without a spreadsheet

For teachers who know a child "keeps making the same mistake" but cannot say which one.

Most abacus errors in a class fall into five or six patterns. A teacher who tracks the pattern knows what to work on next; a teacher who tracks only the score can see the same error for months. You do not need software to start. You need the pattern list, a card with one line per student, and the habit of writing one letter after each wrong answer. Software comes in when you have twenty students and want the card to fill itself.

The six patterns

The codes are deliberately short: you write one after each cross. "5↕" takes a second; "did the complement of 5 the wrong way round" does not get written.

Why the pattern matters more than the score

Two children score 7 out of 10. One made three 5↕ errors; the other made one C, one S and one R. The first child needs five minutes on the 5-complement tomorrow. The second child is tired or rushing, and needs slower problems, not a lesson. The score says they are the same; the pattern says they need opposite things.

The card: one line per student

A printable version of this card is the free mistake observation sheet.

On paper, a sheet with twenty rows (one per student) and five columns (one per lesson). In each cell, the codes from that lesson's problems and homework: "5↕ 5↕ C". After three lessons the row reads itself. A row of 5↕ is a child to pull aside; a row of mixed codes is a child who is rushing; an empty row is a child whose homework you never saw.

The card also changes what you say to parents. "She is at 70%" becomes "she is doing the complement of 5 in the wrong order; we are working on it this week", which a parent can repeat at home.

Reading the card: three things to do each lesson

1. Start the lesson from the most common code in the class. If eight of twenty rows show 10↕, the first five minutes are the 10-complement for everyone, on the big abacus.
2. Give three homework problems of each child's own code. Three, not ten. Then the current level.
3. Promote by the card, not the score. A child with two clean lessons in a row at a level is ready; a child with 9 out of 10 and a 5↕ every time is not.

When the card should fill itself

At twenty students the card is five minutes a lesson; at forty, with homework, it is an hour a week. That is when a tool earns its place. The thing to look for is narrow: when a child types a wrong answer, does the tool work out the *likely wrong bead move* from the wrong answer and record the code, or does it just record the cross? The first kind replaces your card. The second kind is a gradebook.

Soroban Kingdom does the first kind: the child solves on a real abacus and types the answer, the app reconstructs the likely wrong move, shows it as a picture to the child, and keeps the mistake type on the teacher's screen per student and per class. If you already keep a paper card, the codes above map directly onto it.