Hayden Robinson wasn't happy with trash on his Boulder school's playground.

Discarded candy wrappers, dog poop not scooped, trash used as boats on the nearby stream: "It makes me angry," he said.

So the Flatirons Elementary third-grader, joined by the rest of the third-grade class, took a day to clean up the playground and painted a mural as a reminder not to pollute.

"It helps keep the world clean," said third-grader Emma Beck.

The service project was proposed by teaching candidates at the University of Colorado, who spend Tuesday afternoons working with Flatirons teachers and their students.

Other projects included raising money to donate to the homeless and to preserve land in the rain forest. Two second-grade classes raised more than $3,000 through a read-a-thon for Heifer International to buy animals for impoverished families.

"We're helping people in need," said second-grader Sean McElveen.

The 21 CU students are in an elementary social studies class that includes a practicum requirement. Their last day at Flatirons was Tuesday.

"It taught me a lot," said CU senior Tiffany Dent. "I learned how easy it is to do projects like this. You don't think, at so young, the kids would be so excited about it."

Charlie Ruda, another CU senior, said the Heifer project went much better than expected.

"It was awesome," he said. "I've loved it."

He's planning to become a teacher because, he said, "It's the most fulfilling job."

"It's not your typical behind-the-desk job, doing the same thing every day," he said.

For CU junior Carolyn Kirsten, who worked with third-graders, the best part was watching the students realize they could make a difference.

"They realized their potential," she said. "It's great to learn how to inspire social action in children."

Penny Scott-Oliver, a Boulder Valley teacher who also teaches the CU class, said she chose Flatirons because of the high-quality teaching and willingness of teachers to work with CU students. Several of the CU students plan to return to Flatirons for their student teaching.

"Their experience at Flatirons reflects the best in a collaborative relationship between the school district and the university," Scott-Oliver said.

Second-grade teacher Cheryl Spear said her class benefited, with the CU students making it possible to work more with small groups of students. The CU students also presented information on poverty and the various animals used in the Heifer project.

"It's a really great program," she said. "A big part of Flatirons is a belief in community service, so it's a natural fit."

Contact Camera Staff Writer Amy Bounds at (303) 473-1341 or boundsa@dailycamera.com.