Today in class I learned that when you have nothing to say and you are left out of the conversation, you feel bored.

The class started normally enough.  I introduced universal motors by not talking about them.

I asked the class how to reverse a DC shunt motor.  Then I asked them about what doesn’t result in reversing the shunt motor . (No matter which way you wire the DC supply, the motor will only turn one way).  So, if you can hook up the supply either way and still get the same rotation, could you run it off of AC?  The usual suspects had questions or comments, wanting to test their theories.  For once I remembered to shut up.  I asked everyone to spend 7 minutes discussing with a partner their ideas about what kinds of motors could be run off of AC or DC.

They sat in silence for 4 minutes, leafing through the book.  (Answer’s not in the book).

After 4 minutes, I told them the answer wasn’t in the book, and that they would have to develop their inferences based on their own knowledge.  They’re a pretty jaded bunch, so they looked a bit weary.  I asked who had some ideas.  A few hands went up.  I told them that anyone who had some ideas should team up with someone to discuss them.  And that anyone who didn’t have a theory should team up with someone to generate some.  They ruefully sat in pairs and conversation started.

Then it got louder, then it got animated.  I stood back while wheely chairs were spun as people impersonated rotors.  When I heard the conversation veer to a recent hockey controversy, I quietly started making a round of the room.  Conversations got back on track.  I asked groups what their theories were so far, and suggested they consider not only DC motors that could use AC, but also AC motors’ ability to use DC.  No one had considered that, and the conversation got loud again.  At the 7 minute mark, they were just getting warmed up.  I decided to let them continue.  I stood back, consciously deciding to not hover, and realized I wasn’t sure what to do.

When I teach someone how to use a tool, I am adamant about never touching it.  If I need to model how to use that tool, I get my own, but I never remove the tool from a student’s hands.  I have even been known to slap someone’s hand away if they try to remove tools from my students’ hands for any reason less serious than loss of life or limb.  So why on earth do I take the words — tools of ideas and understanding — away from my students?

Today in class I had nothing to say, was ignored and left out of the conversation, and enjoyed a moment of boredom.