My son got a new teacher mid way through this year. He's in 2nd grade and has made really great grades so far. We've noticed this new teacher is grading him differently when it comes to grammar. Let's see what you think the answers are:

"He was driving to fast_____he missed the turn" is it... and or so?

"I'm allergic to cats_____I have 2 of them" is it....but or yet?

Plan on taking him out of this school next year anyway as they got a new principal also and she is "empowered and inclusive"

He was driving too fast and he missed the turn.
He was driving too fast, so, he missed the turn.

I am allergic to cats but I have two of them.
I am allergic to cats.  Yet, I have two of them.

I do not see an issue with using either.  The first one kinda depends on the context of the message to be conveyed.  The second one would depend on the audience.  

I ain't no English teacher though...

Also, if'n that teachin lady wrote "to fast" as opposed to "too fast" she gettin a F from me.

The biggest problem was when we confronted her that either could be used, especially when dealing with a 2nd grader her answer was....I'm just going with what the answer is on the sheet

Without context, …. are correct.

Both, all

My daughter teaches K-6 mostly at the 2nd gr level now... Both would be correct in her eyes, she tells me American is not "Proper" english. Depending on what part of the country you grew up in directly influences this, along with English being a very hard language to master based on all the words that sound alike with different meanings and all the different words with the same meanings.

you can tell by my sentence structure that I ain't no english major, but I can speak American.