A youth orchestra once measured practice by counting completed pages. Students could finish many pages in one evening, but mistakes that had been corrected with a teacher's help often returned at the next rehearsal. The director replaced the page count with a three-date record. On the first date, a student marked the exact bar where the rhythm broke. On the second date, usually a day later, the student played the same bar without the teacher's notes. On the third date, the student performed a different passage that used the same rhythmic pattern. A task was not marked complete merely because the first correction sounded right. It was completed when the student could recover the pattern after a delay and apply it in a new passage. The total number of practiced pages sometimes fell, but the record showed which skills survived beyond the original correction.