I love simple, unexpected science lessons. It was a beautiful day which made for perfect static electricity hair when playing at the park. All he had to do to get the crazy hair was slide down the tunnel slide. Then he grounded himself by jumping off the slide onto the ground or shocking himself on a slide bolt to get his hair back to normal.
Fun quote: J saw the picture and stated, "I look like a puffer fish!"
We had a successful Science Saturday for April! Thanks to everyone who attended.
Preparation for fun:
I made 4 batches of conductive dough: purple (left over from our trial-run of Squishy Circuits), blue, green, and yellow. I also made 3 batches of the insulating dough, without color. Per Squishy Circuits recommendation, I purchased small Safety Glasses from Amazon (affiliate link).
I bought out two local Radio Shack's inventory for buzzers and vibrating motors to end up with 5 of each. These were great because they already had wires on them. Less work for me!
I bought 10 of the 4-AA battery holder with snap connector from Fry's with the 9-volt snap connector. This was also great since I didn't have to solder wires, and I can remove the snaps and store the battery packs without worrying about shorts.
John and I crimped terminals (not exactly what we used, but think something like this) onto each wire. This allowed greater surface area contact for the connections. We also hot glued where the wire connected to the crimped plastic to reduce the pull-out possibilities (kids are hard on things). We also hot glued the joints of the LEDs after we broke one during our trial-run.
All of this preparation paid off. We didn't break the legs of any LED and no wire was pulled out from the crimper. Since everything survived, I now have a classroom set of small electrical components.
The table set-up:
I put down a plastic disposable tablecloth. This helped keep the play dough from acquiring dirt and other park related gross things. Safety glasses were required to participate (provided by us).
My favorite find from cleaning out my parent's house a few weeks ago was this drawer set, which is perfect for electrical components (previous use: Barbie's shoe sorter). Those are original stickers my sister and I put on in the 1980s. It just screams science fun!
Reminder about circuits and shorts:
The battery does not liked to be plugged into the same piece of play dough. There needs to be space or insulative dough between at least two separate conductive dough pieces.
We briefed everyone on "shorts" and how to prevent them. I also made wearing the safety glasses mandatory. We, thankfully, didn't have any shorts.
Totally awesome creations:
I did a happy face (the "hot dog" circuitry is on the underside and the wires stick through the insulative dough to the conductive dough underneath):
Doggy wagging his tail, a vibrating motor (by my husband, John- note the tail flying off at the end):
A few butterflies:
A rocket ship:
An airplane:
A train (that whistled):
Flowers:
Problems we encountered:
The biggest problem was that the dough dried out as we were playing and wasn't conducting well. Reforming/reworking the dough or switching the connector locations solved this problem.
The sunlight drowned out the LED lights, but if we cupped our hands over the play dough circuit, creating shade, the lights burned bright.
During the experiment, we shorted 2 LEDs. Lesson learned: don't connect the LEDs directly to the battery wires. They need resistance which is provided through the play dough.
Please note that due to crazy May scheduling, we will not hold a Science Saturday. We are tentatively thinking about repeating Stomp Rockets for June, with a date TBD.
We were introduced to Squishy Circuits at last year's Maker Faire. I thought they were very interesting, but J was a little too young as a new 3 yr old. Almost a year later, I've decided that J's old enough to try playing with circuits.
What is a circuit?
It's a connection of electrical items through wires/conductive material. Metal, water, human skin are all examples of conductive materials. Metal is intuitive when it comes to conducting electricity. You can feel electricity conduct through your skin if you rub your feet on the carpet and then touch someone else or something metal (static electricity is shocking). You also don't want to be in the water during a lightning storm since water conducts electricity.
How do circuits work?
Each circuit needs a power source (ie. a battery pack) and at least one component (ie an LED, motor, buzzer, etc). Basically, the items in a circuit all need to "hold hands" in some way, without the battery pack being connected to the same side of a component or itself, without a component. If a connection is missing/broken, the circuit won't work. Electricity is also lazy. It likes to take the easiest path around the circuit. If there are two wires, one has a component and one does not, the electricity will go through the wire without the component since it's less work (be careful since this can also "short" your circuit - read below).
Making the Squishy Dough
The "conductive dough" is basically the standard homemade play dough recipe we've been using for J. The salt + tap water makes it conductive.
The "insulating dough" is basically pie crust. It uses distilled water which doesn't conduct electricity. There is also no salt in the insulating dough.
Prepping the components
Per the suggestion of Squishy Circuits, we crimped terminals onto our wires to increase the contact area for better conduction. For consistency, we made all of our positive (+) wires red and negative (-) wires black. The LEDs did not get crimped terminals.
Constructing circuits Please closely supervise your kids to prevent short circuits. The circuit gets grumpy if you try to plug both ends of the battery into the same wire/piece of dough or the electricity goes around a path without a component. This causes a short circuit. The battery can get very hot or explode when shorted.
The best way we found to start with the circuits was to make a "hot dog". We rolled out two "worms" of conductive dough (ours was colored purple) and one "worm" of insulating dough (ours wasn't colored, kind of whitish in color). We made the insulating dough longer than the conductive dough, so the conductive dough didn't accidentally touch. Touching conductive dough pieces together is bad and could cause a short circuit.
With the + (red) side of the battery plugged into on side of the hot dog bun and the - (black) side of the battery plugged into the other side of the hot dog bun, we placed an LED straddling the insulating dough, with a leg in each of the buns. Note that LEDs are directional and only work in the proper orientation. The longer side of the LED is +. If the LED does not work, flip it around. If it still doesn't work, check your connections and make sure everything is properly attached (or "holding hands").
You can add rows of LEDs down the hot dog. We made ours look like a stoplight with red, yellow, and green lights. These lights are in parallel. If I remove a light, all of the other lights remain lit at the same level as they were before I removed the light.
Now if we were to make a "Big Mac" with 3 buns, we can connect the lights in series. If you remove a light, the other light is affected.
You can also add motors, buzzers, and vibrators to your circuits too to see what they do and how they react.
J and his friends' favorite thing was trying to make a face with a light-up nose. We connected a side of the battery to each eye and then connected the LED for the light-up nose. We used extra dough for eyebrows and smiley faces.
So what does this cost?
The dough cost is pretty minimal. We had everything except distilled water in our cupboards.
LEDs run under $1/light. I found 60 larger ones for $20 at a local store.
Motors, buzzers, and vibrators are ~$2-4/piece. Some of these components came with wires already attached.
The battery pack was $1.30. We had leftover wires from our homemade shake table.
The dough is supposed to keep in a zipped baggie for a few weeks. J has already requested to play circuits 4 times since yesterday. Remember, this is a closely supervised activity for the kids. Short circuits are easy to come by and can be quite dangerous. Please do not let your kid do this activity alone.
We'll be doing Squishy Circuits at the next Science Saturday (tentatively April 20th, morning). If you'd like specific details of when and where, please email me using the address on the sidebar << . I give details the week of the event since we depend on the weather.
Update December 2018:
Remember to clean off your component leads before you store for any length of time. Salt of the dough corrodes the metal. Use rubbing alcohol to clean any parts that touch the conducting dough. The little boy above is now a cub scout doing the science elective for Webelos!
