Nature doesn't hold still long enough for a textbook diagram, but a movie can put a whole ecosystem in motion and let students watch the consequences play out. Every movie on this list puts environmental stakes directly in the story, a forest poisoned by a single accident, a habitat bulldozed for profit, a planet buried under its own waste, so students see cause and effect instead of being told about it.
These ten cover a wide range of environmental ideas on purpose, deforestation, conservation, pollution, self-reliance, and renewable energy, because the environment isn't one lesson, it's a web of them. They're ranked by what teachers are actually using in their own classrooms, so this is a record of what already works, not a guess. Find the environmental idea you're teaching, pick the movie, and let your students see it unfold.