OAKLAND, Calif. — Marijuana is the focus of a history and science exhibit, ‘‘Altered State: Marijuana in California,’’ a one-of-its-kind show at the Oakland Museum of California. Set against the backdrop of a California ballot measure this year asking voters to legalize marijuana’s recreational use, the exhibition features artwork, political documents, posters, scientific displays, and multimedia exhibits to provoke debate.

‘‘We have designed an open and participatory experience to engage anyone who has an opinion or wants to learn more about the complex issues,’’ said Sarah Seiter, associate curator of natural sciences.

Thirty-five states have medical marijuana laws, and four states and Washington, D.C., have legalized marijuana for recreational use.

Highlights of the exhibition include specimens of cannabis and a ‘‘Cannabis Confessional’’ that allows visitors to share their private, anonymous thoughts about marijuana.

Associated Press