I'm not sure which box you mean - they appear to be in a logical order to me, so I'm wondering if you see something I'm not seeing, or have somehow been misled by something into making a connection that's not actually there.

With looking again, I think I misunderstood the box. It says The so-called 'scalar product' or 'dot product' gives a scalar as a result. And I think now it is in the right place, but I just didn't understand it. It wasn't obvious to me that it was still talking about vectors. Not sure if it can be improved.

The "cross product" is defined between vectors. That's it, really. I'm not sure what more can be added about that, so I'd welcome suggestions. Maybe I can add that comment in a box somewhere.

You may not need an explanation. That just may be me. Lots of other people seem happy to hear "You can't do x." It seems to be a personal quirk that I always want to know "But, why can't you do x??"

That's useful.

Glad something I said was useful.

But having said all that, the fact that you didn't follow it tells me that perhaps I'm not hitting the right level for an American audience, and that's really valuable information.

Maybe. Maybe not.

I mean it is a clue that perhaps there is a difference and you can ask around and all that. But I don't appear to be some kind of typical American by any stretch of the imagination, so I would be very hesitant to make broad inferences based on me as a single data point. Though, certainly, it's a line of thinking worth investigating.

FWIW, I attended K-12 in Columbus, GA. The Deep South has a long history as being a bastion of poverty and not great education. So you might find regional differences within the US.

(The Deep South is variably defined. It sometimes includes Texas and sometimes not. It sometimes includes Florida and sometimes not. It sometimes includes some of the more northerly edge states. It always includes Georgia and Alabama and a few other states of the American Southeast. These were slave states and they tried to secede, leading to the Civil War. The end of slavery absolutely gutted the local economy and destroyed the government system as the states only taxed slaveholders. The entire system had to be rebuilt and has, arguably, not fully recovered from all that. So this is an area significantly impacted by a long and burdensome history.)

I was one of the top students in my school and, based on my merit scholarship (that I turned down) and placing as "alternate" (third place for the entire state for the subject in question) for the Governor's Honors Program (a residential summer enrichment program for gifted students), there is evidence that I was a strong student, even at the state or national level (the scholarship was a National Merit Scholarship). But the school system I attended likely wasn't a great school system.

Also, I basically memorized my way through a lot of math in high school. I was in my 30s when I began getting explanations that were meaningful and useful to me for some of what I had memorized. For that and other reasons, it is possible that it was covered, I didn't really understand it and I simply don't remember.

Those last few paragraphs are intended to give you some context and inform your follow-up research (should there be any) concerning the American education system.