It’s not uncommon to read sentences like this:
It’s so great to be apart of this group.
The suffix “a-“, in this case, came from the Latin, where it means “not.” Therefore, “apart” means “not a part.” Ironically, then, to say it’s great to be apart of something means you’re not, in fact a part of it.
When we (teachers, editors, grammar nazis, etc.) insist on the space between the article “a” and the word “part,” we’re not just being sticklers–that space changes the entire meaning of the sentence.