The Cool Box Comp.

September 26, 2016 at 12:46 PM Leave a comment

Which cool shoeboxes stayed coolest in full sun on the blacktop? Today, students took before and after temperatures.

In the 15 minute run time, we toured each group’s boxes and they explained their design features. It was a perfect opportunity to do a little correction of thermodynamic misconceptions – common ones are that foil insulates, that dark surfaces attract heat and that water magically cools anything down. This was the right time to give a little direct instruction about evaporative cooling, specific heat capacity of water and sand compared to air, reflection of not just light, but heat too, and the difference between heat and temperature. But in fairly simple terms as it’s important to keep moving and to get to every single student and their box in about 15 – 20 minutes before everyone fries on the blacktop.

Dealing with data from class experiments has been where exciting projects can go to die. It is grueling trying to collect data from every table group onto a central data table on the whiteboard. Then trying to figure out what the numbers mean and if there are any correlations. Just sucks the interest right out and makes me hot and cranky.

 

Instead, I had students calculate their temperature rise, then line their boxes up by temperature rise along a chalk line on the blacktop.

A line-up lets us quickly see if there are features that the cooler boxes tend to share. Plus which boxes gave surprising results. As we stand around right there and look at the actual boxes. It’s just so much quicker and easier than formal data analysis. Obviously less rigorous.

If we did it again, or if this was high school, then we’d also do the quantitative analysis to find correlations between features and the cooling observed. We’d also do a more exhaustive analysis of their experimental set ups and the effect their variable had on temperature.

And then there is beating a lab to death for our purposes in a 7th grade project. I say this as a note to self.

“In general” is a big concept because there were surprising boxes – brown cardboard that somehow was super cool, and full on foil-wrapped and insulated that rose 14 deg.C. But in general, there were some vague trends that they noted. And in some classes, none. And that’s interesting too – what could be happening? Bad data collection? Thermometer problems? etc. The natural assumption is that the exception blows everything out of the water, and that’s not just kids.

I’ll be honest, this part of the project was definitely more stressful and less joyful especially with one class where the weather was cooler outside than in and we had to try it with heat lamps. Lots of instruction, not much action. But in the end, it’s now more ready for next year.

 

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Entry filed under: Class Management, Cool the School Project, Critical Thinking, Data Analysis, Experimental Method, Project Based Learning. Tags: , , , , .

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