Nonnative speakers will exhibit errors of grammaticality more than errors of standardness.
Native speakers will exhibit errors of standardness more than errors of grammaticality.

Since NNS exhibit errors of grammaticality, it means that both types of grammatical language, both standard and nonstandard, need to be taught.
While standard language is necessary for academic work, nonstandard language is necessary for:

• interpersonal communication
• accessing entertainment
• reading novels

The grammaticality/standardness distinction explains why some ESL teachers say “The problem with native speakers is that they write the way they speak, and the problem with nonnative speakers is that they don’t write the way they speak.” Native speakers of English tend to write with informal language instead of using more formal structures and vocabulary, and non-native speakers try to use formal English that they don't know yet.

Because NNS errors will be errors of grammaticality, the errors will always be more noticeable than errors by NSs. Teachers may grade their work lower as a result, or be at a loss as to how to deal with it. There are some strategies to bring fairness into the grading scheme, though.

Consider grading content over expression or to separate the two in the grading rubric in order to be more equitable.
Recognize the difference between errors of grammaticality and errors of pronunciation: different origins require different approaches to teaching.

Dictation exercises are one way to diagnose an error’s origin as pronunciation or grammaticality.

Activity: The Lexicon

Since NNSEs have trouble with grammaticality, teachers need to know how to identify and explain why a sentence may be ungrammatical.

Read the sentences below and mark whether they are grammatical or not.

Sentence 1 is ungrammatical, and sentence 2 is grammatical. The difference in the grammaticality of these sentences is an issue of word choice. The verb sleep is intransitive and the verb feed is transitive.

An intransitive verb does not take a direct object.
A transitive verb takes a direct object.

Now try the following sentences. Again, mark if the sentence is grammatical or ungrammatical.

Sentence 1 is grammatical, and sentence 2 is ungrammatical. Again the grammaticality seems to be connected to word choice, doesn’t it? This means that certain rules seem to be attached to certain words. But this example shows it isn’t the meaning of the words that matters; it’s the grammar of the word.

The concern with the rules that are attached to certain words means we are still working at a word level. That is, we are concerned with the lexicon of English.

Now we can add to that by noting that each syntactic category has subcategories.

Click on chart for larger image. Click on larger chart to go back.

Students must be taught the subcategories of syntactic categories as well as the basic knowledge of what a verb, noun, preposition, etc. is. Particularly tricky can be things like count v. noncount nouns or auxiliary v. main verbs.

Another tricky feature is that meaning can’t always be counted on to help figure out the rules, as we have already seen in the earlier example:

• Her mother made her go.
• Her mother forced her to go.
  

The rules that are attached to words are not the only thing that creates grammatical sentences.

Activity: The Lexicon 2

Mark the grammaticality of the two sentences below:

Grammaticality isn't just an issue of word choice. Word order is an issue, too. It matters how the words are put next to each other. In other languages the order may be different.

For instance, in Spanish, the adjective comes after the noun, not before. So the confusion to a nonnative speaker becomes apparent. In order to teach English to the nonnative speakers or to equitably grade work in other subjects, the teacher must have a conscious awareness of the rules that the student may simply not yet understand.