The acute effect of local homicides on children's cognitive performance by Patrick Sharkey in PNAS
Violence makes it tough for kids in a community to read, even a week after the event, and even if the kids don't witness it themselves. Living in inner city Baltimore, I am exposed to other things that make it difficult to learn. I don't have air conditioning, and city heat is stifling. The only real grocery store within walking distance closed in January. People fight and yell in front of my house.
Suburbanites talk about the city as a dangerous place. Sure, we have higher incidences of theft. Violence is more frequent, but it mostly happens between people with grudges, "don't start none, won't be none." Living in the city is hard, but mostly not from big things, like a car getting jacked; what affects me, drains me, is the environment, and what most affects urban kids is probably that plus lack of access to resources that are normal for me: healthy food, good books, safe, clean spaces to play in.