CEDAR RAPIDS — It’s one of the highest distinctions for a magnet school, and Johnson STEAM Academy is the only school in Iowa that has it.Magnet Schools of America designated the Cedar Rapids elementary school as one of the best in the United States this month and marked it as a model for other magnet schools.As students start the school year Monday in the Cedar Rapids Community School District, Johnson Principal Candace Lynch said she hopes families see the distinction as a sign of the staff’s efforts.“Johnson staff is committed to providing the best education for their kids that we can, and we will continue to do that,” Lynch said.