Panthers right wing Brett Connolly checks Islanders defenseman Scott Mayfield...

Panthers right wing Brett Connolly checks Islanders defenseman Scott Mayfield during the first period of an NHL Stanley Cup playoff hockey game in Toronto on Wednesday. Credit: AP/Nathan Denette

We are not exactly sure what materials the Islanders have available to them inside their Toronto bubble, other than the ping pong table for their team tournament.

Maybe a scrapbook with fading newspaper clips from their 17-game point streak last fall? Or stationery to write long letters back home? Or playing cards for late-night games of bridge?

But if coach Barry Trotz has a chalkboard at his disposal, he might want to use it on Thursday to have his players write 500 times each, “I WILL NOT TAKE SILLY PENALTIES AGAINST THE PANTHERS.”

It is exactly the sort of thing a team with a 2-0 lead in a best-of-five series should not do, allowing an opponent that was teetering an opportunity to feel good about itself.

And it is exactly the sort of thing the Islanders did on Wednesday, leading to a 3-2 loss that extended their NHL qualifying round series to a Game 4 on Friday.

“Obviously, we didn’t execute our game plan,” J-G Pageau said. “Discipline was in our game plan, and we didn’t do it.”

The good news for the Islanders is that they remain a mostly smart, experienced team with a smart, experienced coach, and they have two more tries to advance.

But they would do well to let Wednesday’s assorted mistakes simmer and remember them Friday.

No need here to spend time on every misstep in Game 3.

That includes Scott Mayfield being penalized for flipping the puck over the glass needlessly, and for two penalties coming in the Islanders’ offensive zone.

It is enough to point out two penalties that led to two Panthers power-play goals and illustrate the fine line that separates playoff victories from defeats.

The first came at 2:53 of the second period, when the Islanders were called for having too many men on the ice.

What happened, Coach?

“We had too many men on the ice,” Trotz said. “Usually, [on] the changes, everybody knows who’s up and you watch your guy coming to the bench and one of our players was obviously not watching and he jumped on.

“To me, that’s not being real sharp. That one is inexcusable for me.”

Shortly thereafter, Erik Haula of the Panthers scored the game’s first goal.

It was 1-1 seven seconds into the third when Islanders goaltender Semyon Varlamov saw Florida’s Mark Pysyk bearing down on him and cleared the puck behind his net.

But he did so when said puck was in the zone in which goalies are not allowed to handle them, a rule instituted in part in reaction to the tactics of Martin Brodeur, Islanders GM Lou Lamoriello’s long-ago superstar with the Devils.

Mike Hoffman’s power-play goal following that miscue gave Florida the lead for good. Former Ranger Brian Boyle added another score a couple of minutes later to make it 3-1.

“I made a mistake on that play, very simple,” Varlamov said. “I should have handled the puck better. It cost us a goal.”

Said Trotz, “Obviously, it was a turning point. They were able to capitalize on some momentum there . . . Unfortunately, the puck bounced on Varly.”

Hey, stuff happens. It’s the playoffs. And betting against the Islanders to finish this off would be unwise. But this is a best-of-five, under unprecedented circumstances, so there is no telling what could happen next.

Trotz credited the Panthers with taking advantage of the gifts they were handed, but he said his team can and must do better.

“A lot of the stuff that they got we can clean that up, and that’s in our control,” he said. “So we’re going to have to clean that up. It’s a little bit of a missed opportunity for us to knock them out.”

All could be forgiven come Friday. Win, and it’s ping pong time all weekend.

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