Posted by Ximone Willis
In high school, I was convinced that all my best work was done at midnight the night before a project was due. As a result, despite signing up to lead a session on statistical research methods for the Eureka! girls’ camp weeks prior, I was still frantically boiling water, measuring dough, and cutting up lemons for the squishy circuits at 1AM the night before.
In my defense, I had actually planned out everything the week before: edible water bottles first, followed by squishy circuits, finishing the three hour block off with supersaturated structures. Edible water bottles looked easy enough: create a sodium alginate solution in one bowl and a calcium lactate solution in the other, carefully slide spoonfuls of the alginate solution into the calcium bath, and voila! Mouthfuls of drinking water encapsulated in a jelly-like film. Squishy circuits was to be similarly easy—follow the recipes on the website and you’d get conducting dough to conduct electricity through some LEDs and resistive dough that would block electrical current. Finally, a project of my own making: supersaturated structures! Pour an insane amount of salt into water, heat up the solution until the salt dissolves, and then use the consequent solution to create structures (how this works: you used heat to force a TON of salt into the water. The water doesn’t want that much salt. Disturb the solution, and the water forces the extra salt out. If you do it right, you can selectively disturb the solution to build a small tower).
We would then use statistics to analyze the number of water bottles each girl made, as well as the height of the structures. As for the squishy circuits, they were just kind of an interesting way to fill the time.
The day of the Eureka! girls’ camp dawned bright and way too early. We got started on the edible water bottles, but what had looked so simple in the youtube video apparently required quite a bit of skill in real life. Most of the girls got a thick film of jelly. One girl, however, had some mad skills and made like 15. When we made a rough graph of the results, we got a Gaussian distribution centered around zero (which, in this case indicates that a lot of skill is needed up front).
But no matter! On to the next experiment, which was sure to work (I covertly tested it at the front of the classroom to reassure myself that yes, the conductive dough conducted). To engage the girls, I told them that I had forgotten which dough was insulating and which dough was conducting, and that they had to figure out which one was which.
Apparently our tap water had a high ionic content, because the insulating dough was conductive and the conductive dough was too conductive (it was burning out the LEDs). So, like any good scientist we mixed the two together and soldiered on.
I pride myself on being resourceful (one time I was using a microscope that was very dim, so I replaced the light source with my phone’s flash to get the data I needed). When we needed to heat something up, I got out my trusty plastic Chinese kettle with exposed heating coils, poured in a ton of salt and water, and waited for the solution to become supersaturated.
It took a long time. A really long time. Such a long time that I held a Q&A session with the girls about electrolyte regulation in the human body, because biology is my jam. And it took so long that when we poured out the supersaturated solution, I 100% forgot that (super)saturation is a function of temperature, not of amount of salt.
As you might imagine, this demo also did not work, because I forgot to let the solution cool down to room temperature so that it would spontaneously form crystals.
But it wasn’t all doom and gloom. The girls got to make circuits, learn about salt balance in the body, and most importantly hear about (and see) failure, which is arguably the most important part of STEM. But unlike Thomas Edison and his 10,000 lightbulb attempts, failure is swept under the rug or laughed at. And even though my demos didn’t work perfectly, I got to show the girls that failure is not the end, only a setback.