The education of Luis Severino continues. The lessons learned now are small, but oh so important.

One lazy slider can ruin your night, as Severino learned in a 4-1 loss to the White Sox on Tuesday night at a chilly Yankee Stadium that snapped the Yankees winning streak at eight games.

At the age of 23, that is the painful truth, but the big picture here is much brighter, because the Yankees are getting the kind of young arm they can count on in the rotation.

And on the day their top minor league pitching prospect, James Kaprielian, underwent Tommy John surgery, this was most welcome news for the Yankees.

This is a big difference from a year ago, when Severino was 0-8 over 11 starts with an 8.50 ERA. This loss was nothing like those losses.

Severino pitched a career-high eight innings, struck out 10 and gave up just three hits — but he surrendered two long home runs, and a Pete Kozma error at shortstop in the seventh set Severino up for the loss.

“I feel happy because I battled,’’ said Severino, who retired 18 of the first 19 batters he faced and has struck out 21 over his past two starts. “My confidence is up. I’m throwing my changeup for a strike, my fastball command is good, my slider is good. I just need to be more consistent. Last year I was trying to rush to the plate, trying to throw as hard as I could. This season I’m just trying to hit the glove.’’

Now it is about learning how to win.

Too often in the minor leagues, teams are driven by the pitch count with their young starters. As a result, pitchers really don’t learn how to make that one pitch that can make a difference between winning and losing because they do not extend themselves.

Those lessons are learned on the fly now in the majors. One pitch can make all the difference late in a game. Chalk this one up to a seventh-inning lesson.

In the third inning, the right-hander tried to get a 1-0 fastball by the 5-foot-8 Leury Garcia, but Garcia punished the pitch, driving it into the Yankees’ bullpen for a 1-0 White Sox lead.

That happens.

Then in the seventh, after Kozma muffed a potential double-play grounder by Melky Cabrera to put runners on first and second, Jose Abreu popped up a bunt for the first out.

On a 2-0 pitch, essentially with the game on the line, Severino let go a lazy 83-mph slider that Avisail Garcia crushed for a three-run homer to put the White Sox up, 4-0. Garcia said he was looking for a slider because in his two previous strikeouts, Severino was able to command the pitch.

Garcia got the hanger he was looking for and did damage.

“Being a starter you have to work, you have to run a lot, so when you get to eight innings you need to keep going,’’ Severino said. “I was trying to throw a slider for a strike, and he got me with it.

“They were chasing the slider a lot.’’

In his previous outing he threw more changeups, but this was a night his slider was ripping across the plate, except for that one in the seventh.

The Yankees, meanwhile, could not do anything against old friend Miguel Gonzalez, who went 8 ¹/₃ innings before giving way to David Robertson, who made it interesting by walking in a run before getting the final out on an Aaron Judge bases-loaded grounder to short for the force at second.

Catcher Austin Romine, who has done a fabulous job filling in for Gary Sanchez, noted of Severino, “I think he pitched tremendously. He punched out 10 and he didn’t walk anybody. The slider was pretty dominant. We were able to do a lot of good things with it, throw it backdoor, throw it back foot. There are some good hitters in the league and they are going to hit the ones that hang up in the zone.’’

One late lazy slider made all the difference, a vital lesson learned.