For teachers
Where did the class get lost?
No names, no cameras — only anonymous writing patterns. Hesitation and erasing from everyone’s notes, pooled per 30 seconds. Groups smaller than 3 students are never counted.
From 6 students’ notes on this lecture.
Erased strokes: SQLite · computed in TypeScript · busiest 30 s: 60
Show as a table
| Lecture time | Students who hesitated or erased | Erased strokes | All strokes |
|---|---|---|---|
| 00:00–00:30 | fewer than 3 | 0 | 154 |
| 00:30–01:00 | fewer than 3 | 9 | 147 |
| 01:00–01:30 | fewer than 3 | 0 | 135 |
| 01:30–02:00 | 6 | 57 | 148 |
| 02:00–02:30 | fewer than 3 | 0 | 120 |
| 02:30–03:00 | fewer than 3 | 0 | 180 |
| 03:00–03:30 | fewer than 3 | 0 | 126 |
| 03:30–04:00 | fewer than 3 | 0 | 229 |
| 04:00–04:30 | 6 | 60 | 139 |
| 04:30–05:00 | fewer than 3 | 2 | 139 |
| 05:00–05:30 | fewer than 3 | 11 | 119 |
| 05:30–06:00 | 5 | 25 | 98 |
Top 3 moments to re-teach
Where the most students hesitated or erased
Moment 1: 04:00–04:30
6 students hesitated or erased · 60 erased strokes“Ask yourself: is the x sitting inside something, or next to something? Sometimes you need both rules in the same problem. Take x squared times e to the…”
Moment 2: 01:30–02:00
6 students hesitated or erased · 57 erased strokes“Outer function sine, inner function x squared. The derivative is cosine of x squared, times two x. Be careful: it is cosine of x squared, not cosine of…”
Moment 3: 05:30–06:00
5 students hesitated or erased · 25 erased strokes“is sine x. Two sine x times cosine x, which some of you know as sine of two x. It is not cosine squared x, and it is…”