# 19. Exercises, submissions and grades

Because every sentence and cell has a permanent address, the answer to a verification exercise is an address, and an address can be graded.

## 19.1 Exercises

An exercise is an annotation of kind `exercise` whose `exercise` property holds a `scienting-exercise/1`: an `exercise` kind, a `prompt`, a `key` and a `rule`.

| Kind | The student | The key |
| --- | --- | --- |
| `anchor` | Finds the sentence or cell that supports a statement. | `elements`: each a set of acceptable anchors, with points and feedback. |
| `check` | Decides whether a cited passage supports the citing sentence, and anchors the passage. | A `verdict` with points, and `elements`. |
| `trace` | Follows a value back to its original measurement. | A `chain`: an element per link, in order. |
| `reproduce` | Digitizes a plot and recomputes a value. | A `value`, a `tolerance`, a `unit`, the confirmed `digitization` it comes from, and points. |
| `verify` | Checks a model's `summary`, written with addresses, in which errors were planted. | `errors`: each a set of anchors and the correct verdict, with points. |

The rule's `match` is `same-node` (the student's anchor resolves to the node a key anchor resolves to), `overlap` (and, where the key has a span, the student's span covers at least `min_overlap` of it; default `0.5`), or `chain` (each link matches in order, with credit per link).
Feedback is `{hit, miss}` per element.

## 19.2 Verdicts

| Verdict | Means | As claim evidence, if a person confirms it |
| --- | --- | --- |
| `supports` | The passage says what the citing sentence claims. | `supports` |
| `partly` | It says some of it, or with a qualification the citing sentence drops. | `qualifies` |
| `does-not` | It does not say it, or says the opposite. | `disputes`, or no record when merely irrelevant; the reviewer chooses. |
| `cannot-tell` | The passage, or the student's access to it, is not enough. | No record. |

## 19.3 Submissions

A submission, `scienting-submission/1`, holds the exercise's ID, the document and revision, a pseudonymous `student` ID, and `answers`: `anchors`, a `verdict`, a `chain` of anchor lists, a `value`, or `flags` (each an anchor and a verdict), as the kind needs.
The student's name never enters a submission; the mapping from pseudonym to student stays in the course's records.

## 19.4 Grading

Before grading, every anchor in the key is resolved, and if any is stale nothing is graded with it.
Each element of the key earns its points when any of the student's anchors matches any of its anchors under the rule; a `check` earns its verdict's points when the verdicts are equal; a `reproduce` earns its points when the value is within the tolerance; a `verify` earns an error's points when a flag matches it with the correct verdict.
Points are decimal strings, summed exactly.
The result is a `scienting-grade/1`: the submission, the exercise, the `score`, the `max`, and an item per element with its points, its maximum and its feedback.
`grading.jsonl` grades a hit, a miss and an overlap.

Student submissions are educational records, so they live in the course's private store, never on a public log.