American Federation of Teachers President Randi Weingarten is promoting a terrific idea -- a rigorous national exam that teachers must pass before they are fully qualified to lead a class. An editorial by the Chicago Tribune republished in the Star Tribune (Short Takes, Jan. 2) says that passing such an exam would be "a badge of honor and a sign of competence."

The editorial also says: "The best teachers are magicians. They have the capacity to inspire, to keep a young person focused, to develop the mind and, perhaps above all, to motivate."

Do you suppose a good true-false or multiple-choice exam will pick out these magicians? Years ago, a student asked Thomas Friedman what classes the student should take. The response was to find the best teacher in the school and take whatever class that teacher taught (see "inspire," "focus," "develop," "motivate").

There are magicians in the schools, but I doubt that tests are used to identify them. I also doubt they were magicians early in their teaching careers -- probably like many entering doctors and lawyers.

They got much better over a well-spent time. If America wants to use an exam, let's also support that time to fully develop the magicians, then revere them and pay them so they stay, like boards of directors offer CEOs to stay.