Aug 21, 2014

Summer Special: Squishy Circuits

Electricity + play dough = lights? Awesome!

Today's project: Squishy Circuits

conductive dough (a cooked dough with: water, flour, salt, cream of tartar, vegetable oil, food coloring)
insulating dough (a no-cook dough with: distilled water, flour, sugar, vegetable oil)
battery packs
LED lights (similar to this) (you might also try out vibration motors)
waxed paper (optional, makes clean-up slightly easier and helps define workspace)

What we did:

First, I explained the two forbidden experiments:
1.  Touching the battery pack leads to each other (it will burn out the batteries)
2.  Touching the battery pack leads directly to the LED's (it will burn out the LED's)
Then let them know that pretty much anything else was fair game.

Next, I gave a quick, mini-lesson in electrical currents.  My explanation involved this drawing (the green breaks between the purple represent the insulating dough) and quite a bit of happy little electron humming as they zoom along the path, heading back home to the battery pack and then their groaning with effort as they encounter the insulating dough and are forced to jump over the LED bridge and light up that pesky light along the way before they can return back home.  It was oh-so-technical.  My apologies to scientists and electricians everywhere.

Finally, I encouraged everyone to try out one or both of the layouts I'd illustrated, but to then get creative and design their own squishy circuits shapes.  Here's what they did:

 How many LED's can you light up with one battery pack?
 What if we just cover the conductive dough with insulating dough?
What if we alternate conducting and insulating dough?

 Hmm... that's not working, why not?
 Any why isn't this one working?
 Oh, I see.  I need to put this lead here and this LED here...
 Ta-da!  Now it works!

What if we just skip the insulating dough and use gaps instead?
 What if the dough stands up instead of being flat on the table?
 What's the funkiest shape we can use and still have this work?  An arch bridge?  yes!
 A 3D smiley-face ball?  Yes!
 Squishy slugs?  Absolutely!
 Rainbow?  Why not?
 2D smiley face (with HUGE eyeballs!)?  Of course!
 Even the grown-ups couldn't help but get involved.

 Apparently, this is a Pokemon symbol?
 Wait a minute, how does this one work?
 Oh!  Sneaky underneath "bridges," of course!
What's the tiniest squishy circuit I can make?
 What happens if I attach more than one battery pack?
 What happens if we attach four battery packs?

This was such a fun project!  Everyone was so engaged and enthusiastic and I loved watching the interaction between kids and adults in this program.

Hindsight tips:
-If you want to do this project more than once, you should know that the insulating dough only lasts a few days in the refrigerator (and even less if left unrefrigerated).  The conducting dough can last at least a few weeks in the fridge.
-If dough gets too mixed together, just toss it at the end of the event.  The more mixed it is, the less it retains its insulating or conducting properties.

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