Two and Two?

How come we say "these" pants but we say "this" T-shirt? Now, I know, you are asking, "Why even ask the question?" The difference between "this" and "these" is that the first is singular and the second is plural. They are pronouns. In my English class this week we were praticing using "this" and these" refering to things close to you. We practiced using "that" and "those" refering to things farther away.

A student made a keen observation. She asked, "Teacher, pants have 2 legs and I use "those" and "these". Like, "those are pants." Or, "these are pants". "But you say I need to use 'this' and 'that' when I talk about 't-shirts'". ( This t-shirt or that t-shirt) She said, "I don't understand, a t-shirt has two arms." I'm thinking, yes it does. She said, "Pants--two legs and t-shirt--two arms." She asked, "Why can't I use "these" and "those" for t-shirt?" Like, "These t-shirt" or "Those t-shirt". GOOD QUESTION.

"Two and Two" she said putting her hands down on her legs and then up to her shoulders as if to show me that we really have two legs and two arms. I looked at her wondering if she was serious or if I could let out my laugh. She was so serious. I could not keep my laugh in. "Good point", I said. I don't know why "pants" are "plural" and "t-shirt" is singular. Sometimes our English language just doesn't make sense. I see that more and more through the eyes of my students.