What Can Substitute Teachers Do for City Schools? CityLab

The average teacher misses 9.4 days each school year. Total it up, and by high school graduation, a student will have spent six months of class-time with a substitute teacher. Rather than having a sub plod through an unfamiliar lesson plan or just distribute worksheets, a new model at two Boston schools places local experts in urban farming, animation, robotics, puppetry — you name it — at the blackboard to teach about their field.
Taxing Drivers by the Mile, Instead of at the Pump, The Denver Post

Hybrid and electric vehicles may be a boon to the atmosphere, but they’ve caused some headaches for government administrators, namely, how to pay for bridge and road repairs. Prius drivers travel farther on a tank — functionally discounting their share of the gas tax — so the Colorado Department of Transportation is testing the feasibility of a fairer standard: charging for each mile driven instead.
Can Hypothermia Save Gunshot Victims? The New Yorker

Most people who suffer a traumatic gunshot wound die within an hour. Having lost so much blood, their heart can no longer circulate what’s left. A new procedure at University of Maryland’s Shock Trauma Center, near Baltimore, buys more time by putting the body on ice. When a victim is wheeled in, doctors fill the body with freezing saline, pausing heartbeats and giving them just enough time to sew up the wounds.