Sometimes, in this increasingly rancorous world, connecting the dots is complicated. Other times it’s a simple straight line.

Take, for example, what happened last Thursday.

In the White House, President Trump ignited his latest in a long line of political firestorms by denouncing “shithole” countries in Africa, insulting Haiti for good measure and pining for more immigrants from places like lily-white Norway.

Meanwhile, at the Sanford Regional Technical Center, a substitute teacher got into a jaw-dropping exchange with an 11th-grade student over a trip the student plans to take this summer to Lebanon. It’s his father’s native country and the place the American-born teen spent 10 years of his childhood.

The student video-recorded some of the exchange, in violation of school policy, on his cellphone.

“Oh, you’re getting kicked out of my country,” said the teacher, an older woman whom a school official declined to identify.

“It’s not your country. I’m part of it, too,” the student replied.

“Of course it is my country,” the teacher said.

“It’s my country too, though,” insisted the student.

Retorted the teacher, “It’s been mine longer than it’s been yours.”

Heard enough? There’s more:

Boy: “You really think (Trump’s proposed border) wall scares me? It ain’t doing nothing.”

Teacher: ” ‘Ain’t’ is not a proper word. Talk my language.”

Student: “How many languages do you speak?”

Teacher: “Just one … prolifically.”

Student: “I speak three.”

Teacher, her voice laden with sarcasm: “Good for you!”

Finally, much like our president yearned for more blond, blue-eyed immigrants from the Scandinavian Peninsula, the teacher daydreamed aloud, “When Trump is done … instead of 1,100 in this building, we’ll only have seven.”

The teacher is now history. In a prepared statement issued Tuesday announcing her dismissal, Sanford Superintendent David Theoharides noted, “By policy and practice, our staff works hard to ensure that all our students have a safe and nondiscriminatory educational experience.”

Still, with the student’s video now past the half-million mark on Facebook, this sign of the times lives on.

News and social media accounts since the story first broke Friday follow a predictable pattern.

The teacher, in an off-camera interview with WGME, said there are two sides to the story. She conceded that things got out of hand but maintained she was baited by the kid with the smartphone.

The student, on his Twitter account, said there’s a lot more he didn’t capture on camera. It all started, he recalled, when he mentioned his upcoming trip to Lebanon and the teacher replied, “Well, you can’t come back.”

Online commenters, no surprise, range from those who lambaste the boy for using vulgarities at one point – just like his president, he used the ‘s’ word – to those who argue that the substitute teacher had no business being in a classroom in the first place.

But here’s what caught my eye: In an interview late last week with Portland Press Herald reporter Randy Billings, Superintendent Theoharides noted that the teacher was a longtime substitute for the Sanford school system and is “very well-respected.”

In other words, she’s apparently never behaved in a manner egregious enough to get herself fired. Until now.

So, what happened here?

Was she having a bad day?

Perhaps.

Did the boy in fact “bait” her?

Maybe so, although if anyone knows how to recognize and avoid being baited, you’d think it would be a veteran substitute teacher.

But beyond all of that, as I watched the confrontation unfold, I found myself wondering: Would this have happened in a pre-Trump world?

I vote no.

There was a time in the not-too-distant past when telling a kid of Middle Eastern descent – a natural-born U.S. citizen, no less – that he’s “going to get kicked out” of the country would put you far outside the bounds of acceptable civil discourse.

Sure, there are those who long have complained that the country has gone “PC” crazy, that the language cops are poised to pounce on every off-color remark, that Americans can no longer denigrate one another like we used to in the good old days.

But we’re not talking about political correctness here. We’re talking about professional conduct – or alas, the growing lack thereof.

We see it in the White House, where our deranged president thinks nothing of comparing an entire part of the world to a pit full of human excrement. Then, even in the face of eyewitnesses, he lies about it.

And now, we see it in a Maine classroom, where a teacher feels so emboldened by her “non-PC” president that she not only engages in juvenile tit-for-tat with an adolescent but takes full (and completely off-target) aim at his foreign heritage.

That the teacher felt she could do so now, and not before, is no accident. Trump is the cause and she, by her own reference to him, is the effect.

The Sanford debacle raises all kinds of issues, not the least of which is the proliferation of substitute teachers throughout our public education system.

According to a recent analysis by the Education Week Research Center, 22 percent of Maine teachers missed 10 or more days during the 2013-14 school year. (The national average is 27 percent.)

That’s a lot of subs. Without a doubt, the vast majority of them approach the job with a deep breath, an often-unfamiliar lesson plan and full awareness that, from the moment they walk into a strange classroom, they have a target on their back.

Thus, they need to be more patient, more durable and less flappable than the person they’re replacing. We pay them to educate the best they can, not to preach the gospel according to Donald.

I know, that used to be a no-brainer.

Back before we had a president with no brain.

Bill Nemitz can be contacted at:

bnemitz@pressherald.com