# The Payoff, Feb 2013

### On network analysis

“At first I didn’t understand why we had to learn these complicated methods when we could just do it the simple way you showed us last semester.  But when you get to these complicated circuits, it makes it so much easier.  I do math every night now, even if I don’t have any for homework, because you have to exercise all the time or you lose it.”

### On graphical waveform addition

“I got off to a bad start with this, I had the wrong answers for everything, and I really didn’t know how to do it.  I won’t lie.  But now after taking all these measurements, I’m starting to understand.  And I did really bad on that first quiz — I didn’t even know what DC offset was. But I made up some practice problems that are a little bit different from the quiz, and I can do them now.”

### On AC voltage, sinusoidal signals, and what the time domain really means

“I just realized that the word ‘electronics’ has the word ‘electron’ in it. ” (x2) (After a conversation about how a sinusoidal signal represents a voltage or current that changes over time)

“Is this why we need DC voltage for electronics — so it doesn’t turn off all the time?”

“In an AC circuit, how to the electrons get their energy back after they’ve lost it?” (I love the insight in this question — the synthesis of ideas, the demand for a coherent cause)

### While presenting some routine lab measurements

“How does an electron know how much voltage to drop in each component?” (7 months later, students are suddenly gobsmacked by the totally weird implications of Kirchoff’s Voltage Law)

### During a one-on-one discussion of the group’s interpersonal dynamics

“I find no one in this program is looking for someone to give them the answers.  We might text all night long about homework but it’s never ‘Can you send me X,’ it’s always ‘How can I figure out X?’ “

### While whiteboarding some AC circuit data

“I don’t like saying that KVL applies to instantaneous voltages, because it applies everywhere.”

“But if you say instantaneous, it applies in a general sense. Have you ever seen an AC circuit where the component voltages didn’t add up to the supply?”

### Another whiteboarding session

“Make sure you’re talking about electrons, otherwise it’s not a cause!”

“And that’s supported by the model, because…”

### While designing an experiment

“Do you have a 1uF capacitor?” “No, I guess we can use 100uF and scale it…”  (Students making big gains in proportional reasoning)

### After discussing how a capacitor’s voltage approaches an asymptote

“I never noticed before how much math relates to life — like the idea that sometimes the closer you get to something, the harder it is to get there.  I guess it’s not surprising — because math comes from life.  Math is everything.”