SCHOOLMATH: How to explain coping with the "Show Your Work!" to
  kids (3rd/4th grade) when they start complaining how stupid
  showing your work is. They're right: It's stupid. But it's
  necessary: "Just do the math the way you want in your head, and
  show the teacher what THEY want so they can show their boss (the
  principal) that they're a good teacher, and the Principal can
  show the school district that they're a Good school so that the
  Government will pat the school on the head, say, "Good job,
  little School! Here's your Money!"
  It's the truth. It's not that complicated and it's a logical
  reason why Show your Work is tied to Grades. Personally? I think
  "Show your work" should go away: If you get the answer right,
  you get it right. But, Education Theory still believes they're
  training logical/rational thinkers. Soooo 18th century. Oh well