Teach Fzx - How Many Volts?

We finally reached electric potential difference in Fzx class so I started with a question.

After reminding them that every standard outlet across the fruited plains of the US and Canada has a standard voltage, I asked them to give the value of that voltage.  With answers ranging from 9 to 9,000 volts, there were only NINE Honors Physics students out of 60 who gave the correct answer of around 120V.

Is it really possible that so few students actually know that?

Then I asked about the voltage of an automobile battery.  Most of these answers ranged from 100 V to 10,000 V with only a few answers under 100 V.  FOUR students supplied correct answers between 12 and 15 V with two more coming in at 9 V.

Some argued vehemently that a car must have more voltage than the house because the car has to do so much more work to turn the engine over and start the car. I think it's a confusion of voltage - the energy supplied for each coulomb of charge - and power - the rate of use of energy.  Depending on what's connected to it, the voltage source can supply large power or small power, depending on the current.

Now that I know that we are basically starting from zero knowledge of electricity, I can focus more properly on the basics.
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One connected note - Public peer answers affect each other.  The morning classes gave many more voltage values in the thousands for both questions and the afternoon class commonly answered in hundreds of volts.  Both sets of answers were severely wrong, but the mode values were off by a factor of ten.  I believe this to be a result of student conformity to earlier responses they heard.