Educational posters hang on a wall inside a transitional kindergarten classroom at Ira Harbison Elementary School in National City on April 21, 2026.(Adriana Heldiz)Schools in California are more divided between rich and poor than in 40 other states in the country, according to a new report. That segregation is occurring both between school districts and within them. Nationally, it’s worse than it was three decades ago.This matters because schoo…