Demonstrative Adjectives

Not that anyone who dislikes grammar would remember from the good old school days, there are things called demonstrative pronouns that I find rather easy to grasp. One feature of the demostratives is that they can act as adjectives OR as pronouns, depending on how they are used in a sentence. I was teaching this lesson today to my middle schoolers. One caution that I tried to convey was the use of the not-uncommon "this here" and "them there". (We do live in a rural area...) Most of my students snickered. I thought they would, naturally. They snickered because they here it or say it all the time. I simply tried to reiterate that we don't need to approach our grammar lessons like we speak. Many people, I told them again, do not speak in standard English. We often hear things that may sound right, but aren't grammatically correct.
Though I don't think they got it for the long haul, we'll see on our graded homework if they at least got it for the forty-two minutes I have them. I'm crossing my fingers!