Most teachers use a correction code when they mark written work so that the student can do some self-correction. You can devise your own symbols but this table shows some possibilities.
| Mark | Error Indicated |
|---|---|
| / | A word is missing |
| / | Start a new sentence |
| // | Start a new paragraph |
| Gr | Grammar error |
| Sp | Spelling error |
| P | Punctuation error |
| Art | Error with articles (a, an, the) |
| c/unc | Countable/uncountable error (you can use a/an before countable nouns but never before uncountable noun) |
| Wo | Wrong word order |
| Ww | Wrong word |
| Wt | Wrong tense |
| Wf | Wrong form |
| Irreg | Irregular verb |
| ? | Unclear |