Performance Metrics Glossary

The dashboard shows several numbers per student. Here's what each one means and how to use it.

Letters per minute (LPM)

LPM measures how fast a student writes. Scribble tracks two LPM values:

• LPM (gatekeeper) — speed on the kind of attempts that count toward early progression. Tends to be lower while a student is learning.
• LPM (mastery) — speed on the higher-bar attempts used to confirm mastery. Tends to be higher once a student has learned the letter forms.

The end goal of the full curriculum is 25+ legible letters per minute. Most students reach this after working through the full ~20 hours of practice.

Legibility

Legibility scores how clean the student's handwriting is. The dashboard shows an overall score plus four sub-scores:

• Shape — Are the letter shapes correct? An "a" that looks like an "o" loses shape points.
• Size — Are the letters consistent in size? Tall letters tall, short letters short.
• Spacing — Are letters and words spaced consistently? Not jammed together, not floating apart.
• Slant — Do letters lean in the same direction? Consistent slant is what makes cursive look fluid.

Each sub-score gives you a different lever. A student with great shape but poor spacing has a different practice need from one with good spacing but inconsistent slant.

Attempt outcomes

Every handwriting attempt has an outcome. The dashboard shows recent attempts grouped by outcome:

• Passed — The attempt met the bar for whatever was being checked.
• Mechanical fail — The attempt failed a basic mechanical check (e.g. didn't write a letter at all, took too long to start).
• Gatekeeper fail — The attempt didn't meet the legibility/speed bar for early progression.
• OCR fail — The handwriting recognition couldn't tell what was written.

A healthy student will have a mix of passed and the occasional gatekeeper fail. A flood of OCR fails or mechanical fails usually indicates a hardware problem (pen tip wear, screen protector damage) or that the student isn't engaging.

XP and completion

• XP (total) — Lifetime XP earned by the student.
• XP (period) — XP earned in a specific window (today, this week).
• Completions — Number of lessons, reviews, and other entries completed.

These are activity metrics. They tell you how much a student has practiced; they don't say anything about how well.

Daily breakdown

The dashboard shows a per-day breakdown for the current period: date, completions that day, XP earned that day, LPM that day, legibility that day.

Reading the daily breakdown is the best way to spot:

• A day with high XP but dropping legibility (rushing).
• A day with low XP but rising legibility (slowing down to focus).
• A streak of no activity (taking a break — fine, unless it's stretching long).

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