P.S. Be Eleven by Rita Williams-Garcia

After spending the summer in Oakland, California, with their mother and the Black Panthers, Delphine, Vonetta, and Fern arrive home with a newfound streak of independence. That doesn't sit well with Big Ma, who doesn't like the way things are changing.
Neither does Delphine. Pa has a new girlfriend. Uncle Darnell comes home from Vietnam, but he's not the same. And her new sixth-grade teacher isn't the fun, stylish Miss Honeywell—it's Mr. Mwila, a stern exchange teacher from Zambia.
But the one thing that doesn't change during this turbulent year is the advice that Delphine receives from her mother, who reminds her not to grow up too fast. To be eleven while she can.
Readers who enjoy Christopher Paul Curtis's The Watsons Go to Birmingham and Jacqueline Woodson’s Brown Girl Dreaming will find much to love in this book. Rita Williams-Garcia's books about Delphine, Vonetta, and Fern can also be read alongside nonfiction explorations of American history such as Jason Reynolds's and Ibram X. Kendi's books.
Each humorous, unforgettable story in this trilogy follows the sisters as they grow up during one of the most tumultuous eras in recent American history, the 1960s. Read the adventures of eleven-year-old Delphine and her younger sisters, Vonetta and Fern, as they visit their kin all over the rapidly changing nation—and as they discover that the bonds of family, and their own strength, run deeper than they ever knew possible.