Editor’s Note: Khalil Gibran Muhammad is the Ford Foundation Professor of History, Race and Public Policy, an organizer of the Freedom to Learn movement and co-host of the Some of My Best Friends Are podcast. The views expressed in this essay are his own. Read more opinion at CNN.Americans are losing the freedom to learn. Several states across the country have imposed bans on books, K-12 educational curricula and diversity programs in recent months. In fact, every state but one has at least attempted to restrict the right to literacy and the free exchange of ideas, according to a recent...