“Isn’t the beach great?” one preteen asks another as friends cavort on the sands of Limantour Beach. Little do they know that one of their companions is about to turn into a trash monster: a screaming creature sporting a Viking-like horned helmet and is covered in litter. The trash monster has a pretty good time chasing the others and turning them into trash monsters, too, but she eventually has some regrets. “What have I done?” she cries, then dutifully picks the litter off her friends and places it into a bag for proper disposal. Later, the monster, whose real name is Faolan Cadiz, apologizes: “I littered on the beach, then the next thing I knew, I was hurting my friends.” The scene is from a two-minute short film made by students at West Marin School—Ms. Cadiz, Grace Rodriguez, Emily Cardwell, Max Wessner, Hiroki Coyle, Santiago Gomez, Liam Riley, Paul Miranda and Gabriel Diaz, all under the guidance of Julie Cassel—that won second place in the junior high category of the San Francisco International Ocean Film Festival last weekend. The festival is 12 years old and spotlights films that focus on marine life, ecosystems and stewardship. It was the fourth year of the student film competition, said Jeanene Taylor, the student film competition coordinator for the festival, and for the first time it offered awards for middle school and high school separately. They used to be lumped together, but the caliber of high school films spurred the festival to give the middle schoolers a chance to shine, too.