Joe Girardi has yet to fill out his first regular-season lineup card with the Phillies, but the skipper joined a pair of virtual math classes at William M. Meredith School on Wednesday to go over the process -- one that involves a bit more math than most of the students expected.

Girardi, who graduated from Northwestern in 1986 with an industrial engineering degree, joined a video call to lead two math classes (one each for sixth and seventh grade) alongside instructors Jessica Tilli and Alex Piazza.

"I want to show you all the importance of math in baseball," Girardi said at the beginning of his first session. "Sometimes we don't equate math to baseball, but it's so heavily used on a daily basis. Math is really all about all of its different applications in life and how we use it, and it's going to be that way more and more as we move forward."

Girardi began his baseball-centric math lesson by providing the students with a list of nine current and former Major League players and a corresponding batting average for each. He then asked the students to fill out a batting order based only on the information they had at their disposal.

While some students simply penciled in the players from best batting average to worst -- a strategy that Girardi acknowledged used to be the norm -- others sought a more balanced lineup by scattering the best batting averages throughout the lineup. A few even said they wouldn't base it solely on batting average, something that obviously caught Girardi's attention.

"Sometimes batting average can be very misleading," Girardi acknowledged, before delving into a breakdown of on-base percentage, slugging percentage and OPS.

After a brief explanation of each stat, the presentation flipped to a chart featuring a full array of statistics for each of the nine players, including home runs, RBIs, batting average, on-base percentage, slugging percentage and OPS. The catch, however, was that some players simply had a list of their raw totals in the OBP column in place of a percentage, leading Girardi to ask the students to manually solve for that player's on-base percentage.

Though the skipper provided the on-base percentage formula and let the students calculate it the old-fashioned way, he pointed out afterward that they simply could have subtracted each player's slugging percentage from their OPS -- both of which were provided -- to get the answer.

"That also shows the importance of listening," Girardi joked, as many of the students let out a groan.

With the students fully briefed on the various rate stats, Girardi then provided a brief overview of what he values the most for each spot in the batting order. After explaining the importance of having players with a better OPS higher in the order -- with a weight on on-base percentage at the very top followed by a weight on slugging percentage -- Girardi asked the students to once again fill out a lineup with those same nine players, this time using all of the information provided.

Sure enough, some of the players who had a lower batting average -- and thus were hitting near the bottom in most of the original lineups -- made significant jumps in the order, thanks to stronger on-base percentage and OPS numbers. Likewise, some of the players with moderately high batting averages, but low on-base and slugging percentages, dropped in the new lineups.

"That's why baseball has such huge analytical departments now," Girardi said. "Numbers always tell a story, but maybe some don't tell the whole story. But still, numbers certainly tell you something -- and that goes for everything in life, not just baseball."

To prove his point, Girardi called on a few students to ask what they wanted to be when they got older. The first student said she wanted to be a math teacher or a baseball player. The next said he wanted to work in sports as a coach, general manager or player. Yet another said he was interested in becoming an engineer, the same educational path Girardi went down during his playing days at Northwestern.

"I'm not asking you to fall in love with math, but I'm asking you to understand how important it's going to be no matter what you decide you want to do with your life," Girardi said. "I know some of you may not like math, but I ask that you embrace the critical thinking aspect, because it's going to help you be better in anything you choose to do in the future."

Girardi saved the last few minutes to field some questions from the students, who quickly transitioned the topic from math to baseball. After answering some questions about the Phillies' lineup (yes, Didi Gregorius will be the starting shortstop) and whether there will be a 2020 season (Girardi responded by crossing his fingers for the camera), the Phils' skipper ended the day by striking a deal on the students' behalf.

"If we're able to win the World Series," Girardi said, "you have to make a deal with Mrs. Tilli that you get the day off of school for the parade."