They’re racially diverse, in a city where most public school students attend schools that are vastly majority African-American. At the three charter schools, between half and three-fourths of students are nonwhite.

The schools also all operate in central-corridor, relatively diverse neighborhoods that are seeing development and families moving in — in some cases, just to attend those schools. They were started by parents and thrive on a grass-roots sense of community.

They’re small schools — City Garden is the largest at 221 students — and can therefore provide an intimate and personalized environment for students. They offer programs not commonly found in other public schools, such as mindfulness exercises and Singapore math at Lafayette and a St. Louis Zoo “micro-school” program at The Biome.

Most notably, these schools receive up to three times more applications than they can accept, even though Lafayette and The Biome are too new for the state to evaluate how well they perform academically.

When demand exceeds space, charter schools use random lotteries to admit students, which appear to give everyone the same shot at getting in. But the application deadlines, which are often in February, for those lotteries frequently end up favoring wealthier families.