when to use "that" or "who" [closed]

I'm confused about when I should use "who" or "that." Should the sentence read: I am a coach that specializes in helping students with math. Or should the sentence read: "I am a coach who specializes in helping students with math.

Solution 1:

I am a coach who... You're speaking of yourself... You aren't a thing...in which case you'd say "that" but a person.

I rode in a coach that carried six people.

I am a coach who specializes in helping students with math.

Solution 2:

John Lawler is almost correct.

The choice is indeed mostly up to the speaker, and as mentioned, does not affect meaning or grammaticality. However, "who" should only be used for people and animals (arguably only familiar animals).

Consider:

That's the table who I bought yesterday.

It doesn't really make sense. You have to use "that":

That's the table (that) I bought yesterday.

Even then, though, the "that" doesn't have to be used.