The students of Room 22 are going to change the world, and if they have to dip their index fingers into wet glue for the rest of their lives to make it happen, so be it.

“It’s not a big thing to get glue on your fingers,” said Gurpartap Singh Sahi, 8, who spreads glue with his finger every day instead of using the glue sticks that are seemingly ubiquitous in every other third-grade classroom on planet Earth.

And the same applies to ordinary pencils. They’re painted yellow. They’re part of the problem, too.

So it goes in Berkeley, where the two dozen third-graders at Oxford Elementary School have forsworn their old ways in order to make their classroom nearly 100 percent sustainable.

The problem with glue sticks is that their barrels and caps are made of plastic. When the stick is used up, the plastic goes into the landfill. And the problem with ordinary pencils is that the paint-flecked shavings they produce in the pencil sharpener aren’t recyclable, either.

The sticky-fingered students of Room 22 have somehow managed to eliminate their classroom trash can altogether. An entire school year’s worth of trash for the whole classroom fits neatly inside one small mason jar, which the students and their teacher, Jacqueline Omania, would like very much to show you and have you photograph and admire, as much as a jar of trash can be admired.

It’s some jar. Crammed inside are a few plastic bags, hundreds of contaminated pencil shavings from the semester’s non-enlightened first weeks, one evil glue-stick carcass and a few paper clips that one 8-year-old student, as part of a nervous habit, liked to unwind and straighten before the class persuaded him that fraying the edges of a scrap of cloth was just as effective, and better for the environment.

There’s also a single wrapper from a granola bar, long since eaten. Since it was a Berkeley granola bar, the wrapper said that its ingredients included broccoli. No one remembers eating it or ditching the fateful wrapper, a transgression now shared by all.

Everything about a sustainable classroom is educational. The class sewed cloth shopping bags as a craft project. And Omania turned the unused plastic cups and utensils (the class has switched to metal cups and bamboo utensils) into a math lesson.

Eighteen hundred plastic cups, 1,260 plastic forks and 1,072 unused plastic spoons total 4,132 things that aren’t in the landfill this year. It’s a big number, one student said, the kind you need a comma to write, preferably with an unpainted pencil.

Room 22 says it’s not enough to change one classroom. It’s after bigger fish. In recent days, the students made presentations to the City Council and to the school board.

“Our generation is the one that has to help,” Fiona Groth Reidy, 9, told the school board. “If a class of 9-year-olds can do this, anyone can do this. You need to buy unpainted pencils.”

But changing the world is hardly a slam dunk. Last year’s Room 22 students did the sustainable classroom stuff, too, and then they they graduated to fourth grade. Their new teachers at Oxford are great teachers, they said, but not sustainable teachers — and the glue sticks came back.

“We don’t really stick our fingers in glue any more,” said Room 22 alum Alyssia Lewis, 9. “Sometimes I wish we could.”

Steve Rubenstein is a San Francisco Chronicle staff writer. Email: srubenstein@sfchronicle.com