BOSTON (AP) — U.S. guidelines that say students should be kept 6 feet apart in schools are receiving new scrutiny from federal health experts, state governments and education officials working to return as many children as possible to the classroom. The distancing guidelines have remained a major hurdle for schools as they aim to open with limited space. But amid new evidence that it may be safe to seat students closer together, states including Illinois and Massachusetts are allowing 3 feet of distance, and others including Oregon are considering it.