It's something that started at Grand View Elementary School back in 2009 and has grown to 516 schools, 41 states and several countries.
"Our project was to go down to Dockweiler Beach, pick up trash and then make a bunch of pledges to help people clean our Earth cleaner," said Agens.
"This school was producing about 30 to 40 bags of trash every single day, just at lunch time. Now they're down to producing just one and half bags of trash a day," said Kim Lewand Martin, director of programs and communications for the non-profit Grades of Green.
It's a stunning result considering there's about 700 students. About 70 percent of the school partakes in "Walk to school Wednesdays," saving fuel and greenhouse emissions.
Forget posters and flyers, they publicize school events by chalkboard and e-newsletters. And they've got lunch down to a science. Meals are brought in reusable containers, and water bottles from home are filled at filtered water rehydration stations.
Any uneaten food goes to compost. So does brown paper towels kids use to wash hands in every classroom.
It's often hard for parents to learn these environmental messages, but not for kids. That's why they have student ambassadors to help spread the word. Grades of Green enlists the help of 60 students each year.
Like fourth grader Lila Murphy who offered a handful of ideas to help the environment.
"One of them is to take five minute or less showers. Another one is to use both sides of the papers, turn off lights when you're not using them, pick up litter," said Murphy.
With the intention of making a better planet, efforts don't stop at school.
"We've had kids go before the city council and ask for plastic bag bans and Styrofoam bans. And they have been successful in having entire cities change the way they do business," said Lewand Martin.
The Grades of Green program is free to schools through grants, donations and fundraisers.