> ## Documentation Index
> Fetch the complete documentation index at: https://docs.timeback.com/llms.txt
> Use this file to discover all available pages before exploring further.
# XP system
> How Timeback measures learning effort and progress
## Why XP exists
Education software usually forces a false choice: track **time** (which measures presence, not learning) or track **accuracy** (which ignores how much work was done). A student who spends 30 focused minutes mastering fractions and a student who clicks through the same lesson in 5 minutes can both show "100% complete", yet the learning that happened is vastly different.
XP solves this by combining **effort** with **proof**. It's a single metric that captures both how long a student worked and whether that work produced verified learning. This makes it possible to compare outcomes across apps, content, and students.
## The design
**1 XP = 1 minute of focused learning.**
Anchoring XP to real time creates a universal unit that every app in the ecosystem shares. When a school sees "120 XP today" on a student's profile, they know it represents 120 minutes of verified learning work, regardless of which apps generated it.
Two concepts make this work:
| Concept | Definition |
| --------------- | ------------------------------------------------------------ |
| **Expected XP** | How long a focused student should take |
| **Awarded XP** | What the student actually earns, based on verifiable metrics |
**Expected XP** is calibrated at the content level by the app developer. It represents the time a focused student should need to master the material.
**Awarded XP** is what the student earns after completing the activity. It depends on whether mastery was demonstrated and how efficiently the student worked.
## How XP is awarded
Not all effort is equal. XP reflects the quality of learning, not just the fact that something was done.
| Outcome | Effort quality | XP result |
| ----------------------- | --------------- | ------------------ |
| Mastered | Focused | Full XP |
| Perfect (first attempt) | Focused | Full XP + Bonus XP |
| Not mastered | Focused | 0 XP |
| Mastered | Wasteful | Partial XP |
| Any | Gaming/cheating | Negative XP |
A student who masters the material efficiently earns full XP. A student who gets it right on the first try earns a bonus. A student who works hard but doesn't reach mastery earns nothing, because XP represents *verified* learning, not just participation.
No XP is awarded below 80% accuracy. This discourages students from speed-running content or
guessing until correct.
### Why negative XP?
If XP can be earned without real cognitive effort, the metric loses its meaning. Negative XP exists to discourage behaviors like exploiting answer patterns or using external tools to bypass assessments. Rather than simply awarding zero, the system actively penalizes detected gaming so that the XP totals across the ecosystem remain trustworthy.
## How XP flows through the system
When an activity completes, the app reports the XP earned. Timeback processes activity data through the gradebook pipeline and aggregates it the student's [profile](/beta/build-on-timeback/sdk/user-profile), where it's surfaced in dashboards alongside XP from other apps.
Because every app reports XP using the same unit, the platform can answer questions that no single app can:
* Did 30 minutes in App A produce more learning than 30 minutes in App B?
* Which content sequences produce faster mastery for which students?
* Is a student's total daily effort on track?
How apps report XP through the SDK
The rules that protect XP integrity