[susan53]

I always teach am is are.

My students are Italian and have 3 different ways of saying what in English translates as you : tu (informal, singular) lei (formal, singular, actually 3rd person - she) and voi (plural). I want them to understand that the tu equivalent (thou) no longer exists, the 3rd person option has no relevance to English and that you is actually the old 2nd person singular (ye), now used for both singular and plural, formal and informal. But grammatically it remains plural and this is why the verb are is used, the same as for we and they. So I always tabulate the verb as :

I am
He /she / it is
We / You /They are

This works with European learners who have the sing/pl formal/informal distinctions in their own language, but I might take a different approach with learners whose own language behaved differently.