The Sensuous Fly Girls (1976)

Four slim white teen girls in school uniforms start things off in a classroom. Two brunettes with long straight hair focus on each other, going down in dim POV shots. The action moves outdoors to a forest, where one of the teens gets on her knees to suck off a dude with a decent cock. The camera stays close, showing every detail. The scene keeps switching between the girls eating each other out and the outdoor blowjob. No fucking between the guy and girls, but the oral action is solid, and the schoolgirl vibe adds a nice touch.