SPELLING:
1. The word is misspelled.
Examples: Dolpins are the friendliest animals.
          Dolpins: Dolphins

2. It is a compound noun.
Exanples: Our teacher needs help erasing the black board.
          black board: blackboard

3. There is faulty spacing between words (combined words).
Examples: My favorite icecream flavor is chocolate.
          icecream: ice cream


INAPPRORIATE WORD:
1. If it is an existing and valid word.
2. Replacing any word with another word other than a conjunction, preposition, or article
3. Omitting unnecessary words/phrases (not conjunction, preposition, article)
4. Errant noun forms (singular to plural, and conversely)
5.  Errant verbs (not verb forms)
6. Change in word form/function.

Examples: I go to school everyday.
          everyday: every day

Everyday vs. every day:
Everyday as a one-word form is an adjective meaning “ordinary,” used to describe something usual
Example: These are my everyday clothes.
Every day as a two-word phrase, is an adverb used to explain how something is done.
Example: I go there every day.