I don’t know about you, but my students are always desperate for rules : an equation that can be applied to a grammatical structure which is always true. We, as teachers, know that for every rule we give our students there are always exceptions. And they hate us for it.

Take for example the subject-verb agreement of there + be. From an early age we teach our students the following:

Use There is when you are talking about one object, e.g. There is a new boy at school.
Use There are when you are talking about more than one object, e.g. There are two books on the table.

And yet English speakers use There is with a plural noun quite frequently and it doesn’t sound wrong when they do so. You may say that it is only used orally, but if you google “There’s two”, you’ll find approximately 901,000 results. You might add that we can’t expect every article on the Internet to have a perfect grammar structure, so look again for “There’s two” EFL and you’ll see that even English teachers write this structure.

At the end of the day, in written English it is incorrect for the time being and telling your students that it can be used orally will possibly confuse and irritate them, as it doesn’t fit in with the nice equation they have in their heads. Also, the likelihood is that when they hear it used in a sentence, they won’t pick up on it as it will be unstressed and is superfluous to understanding the meaning of the sentence.