HARVARD -- Students at Hildreth Elementary School sat in rapt attention on Earth Day for a series of presentations aimed at raising awareness about environmental protection.

Students in each grade participated in projects that will become part of the school's open-air courtyard:

* Kindergartners and first-graders planted flower seeds to provide nectar for butterflies

* Second-graders made suet feeders from cornmeal, flour, sunflower seeds and raisins

* Third-graders made feeders from recycled soda bottles

* Fourth-graders made butterfly and bird houses

* Fifth-graders made bird baths from clay flower pots.

All work was directed by art teacher Cindy Harris during the week before April vacation.

Monday's guest speaker, Steve Matson, is a member of the Harvard Energy Advisory

Committee and a professor of chemical and biological engineering at Tufts University. Matson addressed fourth- and fifth-grade students. In recognition of the work of the Energy Advisory Committee and installation of a solar array atop the school's gymnasium, Matson discussed the sun's contributions to the environment and, in particular,

cycles that produce energy.

Matson handed out coal samples, which were passed among the students. The fossilized carbon remains the most heavily used fuel in the generation of electricity.

"A vast majority of scientists" agree that carbon emissions from burning coal "is causing the planet to warm," he said.

Drought and food shortages, melted polar caps and more violent storms can result, warned Matson. A conversion to renewable-power sources like solar is the salvation, said Matson, who said he personally powers his home with wind power.

The solar array atop the school gym was installed in January. Since then, the system has generated 2,297 kilowatt hours, or enough to prevent the release of one ton of carbon emissions into the atmosphere.

Matson praised Hildreth for its "reduced environmental footprint" with the new solar system up and running. Fellow Energy Advisory Committee members Jim Elkind and Bill Blackwell were on hand.

Bromfield students Emma Sullivan and Olivia Philip spoke about the newly-formed "Bromfield Green Team" that works on environmental issues. One club project is for Bromfield to go energy-free for a day in May. The team is also looking to promote changes in the school lunch program to cut down on paper waste.

Fourth-grade teacher Kathy Kittredge applauded her students for constructing cardboard "solar homes," which modeled the use of awnings and solar panels to decrease energy use at home.

"This is about everybody doing a lot of little things," said Matson.

Follow Mary Arata at twitter.com/maryearata.