I have experienced a lot can be used.
The only way my words work sometimes is if I close my eyes, then they don’t get stuck or muddled as much.
You could try to see if that works in class, just tell the students that you have to check to see if you dropped it down the back of your eyelids?
Ha, glad its not just me!
I too have brain fog a lot of the time:) One thing I do often is say the opposite word… if I mean to say summer I say winter ??? Or if I am eating and start talking I drop the food into the sentence 
But as I am still a newbie here I have to say you all sound and type so eloquently. This really is encouraging as I love to come online and join in
My brain takes a while to heat up. It’s like the old TVs, you have to switch it on a while before you want to use it in order to warm up the tubes. And even then quite often I forget the word that’s coming next in the sentence. So irritating when people think they know the word you’re about to use and are wrong, you’ve just not retrieved it from the dark corners of the brain yet. It flows more fluently when typed because you can’t see the hesitation for memory.
Se
Ha, exactly Sue! I prefer typing for that very reason: it gives me time to proofread everything I want to say before hitting the dreaded ‘enter’ and no matter how long it has taken me to redecipher all my words(!), the reader is none the wiser! 
Plus, now we have the lovely ‘edit’ button, we can correct our words when our brains have written toothbrush instead of bookshelf. (So where is the ‘like’ button?)
^^^^Damned that missing button!
Haha, Today I told my son I was going to do something yesterday (when I meant tomorrow!) …seems to be happening more and more often lately…much to the amusement of my family!