Marley Dias loves books, but last year, the 11-year-old became frustrated with what she was reading for school. “I didn’t see any black girls in the books we were being assigned,” Dias says.

So began the ultimate book drive. Using the hashtag #1000blackgirlbooks, Dias began soliciting donations of books about black women and girls. Her movement came at a time when fewer than 10% of children’s books have black protagonists, studies show.

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Dias’ campaign led to an appearance on “Ellen” and a set visit with Ava DuVernay, the director of “Selma” and “13th.” DuVernay felt an instant connection with Dias, who grilled the director about diversity in the workplace.

“I just was fascinated by her and nourished by her,” says DuVernay. “She’s a dynamic young woman who has a dynamic idea, but a lot of us have dynamic ideas, and we don’t follow up dynamically. We don’t execute.”

The director and the tween activist bonded in other ways, too. Growing up as a film fan in Compton, Calif., DuVernay also had been disappointed by the lack of tales about people of color. There were a few notable exceptions — chief among them “West Side Story.”

“I was mesmerized by the scope and the scale and the beauty of the brown people in the film,” says DuVernay. “To see Rita Moreno doing her thing and looking like friends who lived in my community — I remember that being a real formative image.”

Now DuVernay is doing her part to provide cinematic touchstones to which girls like Dias can relate. Meg, the protagonist of DuVernay’s next project, a big-budget adaptation of “A Wrinkle in Time,” will be played by a black actress, Storm Reid. In the Madeleine L’Engle novel, Meg is white.

“I wanted to make sure all girls see themselves in the film,” DuVernay says.

As for Dias, 1000 Black Girl Books has expanded its mission. Beyond her New Jersey school, the organization is working with six other schools and has distributed more than 8,000 books. Dias, who hopes to one day be a magazine editor, says she has learned the importance of getting involved. And she has some advice for other kids — and adults — who want to make a difference: “Start with your passion and always do something that’s true to you.”