Make Mistakes Safe

The steps

1. Tell the class why you want the wrong answers. Explain this before your first big check with a new class, and repeat it whenever a check matters.
   When I check, I need to see the wrong answers. They tell me what to teach next. If you hide them, I teach the wrong lesson.
2. Receive every answer in the same voice. Use the same level phrase whichever way the answer has gone.
   Thank you. Talk me through it.
   Keep your face as even as your voice. Students tend to notice your expression before they hear your words.
3. Run checks that let wrong answers reach you. Ask everyone at the same time: boards, fingers for A to D, or a hinge question (see The Hinge Question). Before the check, note the wrong answer you expect and scan for it. Hands-up alone mostly shows you the students who are already right.
4. Put the common wrong answer on the board, with no name attached. Write it out in your own handwriting and attribute it to the room as a whole.
   This was on about ten boards. There's sensible thinking in it. Where does it go wrong?
5. Work the error to a fix, then check again. Trace the thinking behind the wrong answer until the class can say where it breaks down. Then ask a twin question, a near-copy that tests the same idea, and scan again. A surfaced wrong answer should end in a corrected attempt.
6. Show that honesty paid. Say aloud what the wrong answers have changed about the lesson.
   Ten of you showed me that mistake, so we fixed it today instead of finding it in the test.

How you’ll know it’s working

• Boards showing wrong answers stay up as steadily as boards showing right ones. The quick flip-down and the sleeve-rub tend to fade within a few weeks.
• When you ask "who else had this?", count the hands against what you saw on the boards. Over three or four weeks, the two numbers should move closer together.
• Students begin to report their own wrong answers unprompted: "I put B. I doubled instead of squaring."
• Across a unit, the misconceptions appearing in books and quizzes are ones your checks have already caught, and marking produces fewer surprises.

Weigh it up

Why it’s worth it

• Your checks start telling the truth. The gap between what students show you and what they actually think narrows, which improves every decision you base on a check.
• Misconceptions surface during the lesson, while there is still time to fix them for the whole room at once, rather than one book at a time in the marking.
• Participation improves. Students offer answers they are unsure of, which is exactly what Cold Call, hinge questions and boards need in order to work well.
• It changes how students treat each other. When you receive errors evenly, laughing at a classmate's wrong answer loses its licence, and the room tends to follow your lead.
• It costs nothing to run. The moves amount to tone, phrasing and a board pen, applied to checks you already do.

The costs

• The whole technique lives in your reactions, so it has to survive your tired days. One sarcastic reception of an honest answer can set you back weeks.
• Working through a wrong answer properly takes a few minutes, and in some lessons you will trade coverage for the fix.
• Anonymising requires small, repeated pieces of stage management: rewriting answers in your own hand, collecting boards, choosing words with care. None of it is difficult, and all of it is deliberate.