In this May 30, 2016 photo, Maria Arias, 14, quickly uses the calculator on a friend's cell phone to figure out why she has errors on her homework, during her accounting class at a public high school in Caracas, Venezuela. Arias' accounting teacher recently went missing for a week and a half, and when she showed up again, she limited herself to correcting homework. (Photo by Ariana Cubillos/AP Photo)
