Sparked interests and water analogs

Today, on the way to visit friends, my daughter asked me probing questions about one of my favorite little obsessions: traffic signals.

First off, I should note that we are a question-friendly home. If I had to guess, I’d say that there are at least 379 questions asked per day. And if we field even half of those, we are doing well.  And yet as exasperating as the job can be, I can sympathize with my kid because I too was a terribly inquisitive preschooler.  I remember always needing to know the whys and the hows.

So, among all the “why was rest time so looooong?”s, when the big questions surface I get excited.  These are the questions where I can clearly see how her mind is working, churning over the available information that she’s sussed from her surroundings.

das blinken traffic lights
das blinken traffic lights

She asks me today:

Daddy, how do the lights turn colors when the batteries die?

Developmentally, she is somewhat fuzzy on the knowledge of power sources.  She knows of batteries.  In fact, I’m pleased to say that my kid knows the proper polarity alignment of double and triple As.  Battery education is a logical building block of power sources for young children, if you think about it.  Batteries are quantized; they are small, portable, tangible pieces of information that produce energy for all of our Fisher Price possessions.

But when we move outside of the battery domain and into the abstract world of “wall current”, things get a bit more fuzzy.  I told her that all those beautiful traffic signals light up in a different way.  The time was here, her mind was ready — the water analogy.

A great tool for explaining the nature of electricity is fluid dynamics.  I told the kiddo, “Pretend that those ‘ropes’ holding the lights are straws.  Now think of electricity like water.  It flows down the ropes like water in straws and makes all the house lights turn on, and our hair dryers blow, and our microwaves glow.”

For now, she was satisfied with the explanation.  I asked her if she would like to learn more about making little colored lights blink in daddy’s workshop.  It’s going to be a fun year.

For you other inquisitive minds out there, here is a page that delves much deeper into the analogy.  It’s a great resource.






3 responses to “Sparked interests and water analogs”

  1. Eliot Avatar

    Nice. I’m pretty fascinated by signals too. Becoming a cycling instructor has been a really educational process about traffic flow and patterns. Cyclists can take advantage of huge gaps in traffic by waiting after a “pack” of cars to go; often waiting for a green light to turn on to a major road can allow minutes of quiet time, even during peak traffic on major roads.

    Also, I’ve started getting interested in how the signals influence behavior… for instance, in many suburban areas the signals are very long so the incentive to run the red light is much higher. In the urban core, blocks are shorter and so the signal time is shorter (can’t let the queue get too large), less people illegally run the lights.

    When a student instructor at LU made the water analogy, that was the first time that voltage and current “clicked” for me. Brilliant analogy and so easily remembered. It really gives electricity make sense.

    1. Eliot Avatar

      D’oh, can’t edit comment. “It really helps electricity make sense.” Even if my Engrish doesn’t.

    2. Rob Avatar

      Interesting observations! Traffic is indeed a curiosity of mass psychology.

      One of these years I think it would be fun to get into signal engineering.

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