So, for a while I’ve been struggling with how to introduce my qualitative energy unit, which I use to divide up two chunks of my experimental design and analysis unit. Students in my ninth grade classes haven’t had really solid slope analysis skills to call upon at the beginning of the year, so I need a unit that’s thought-provoking and fun to postpone this quantitative work and let the math department do their thing. A qualitative energy unit is perfect for this, but since we don’t have any OTHER physics terms defined the concept of energy is hard to roll out in a way that’s consistent with what Eugenia Etkina has termed “The Arons Principle” – that all concepts must be identified and explored BEFORE they’re given a name. (If this sounds familiar, that’s because I discussed this in a post last year.)
The solution that I arrived on, on an ingenious suggestion from the folks at PhET (@PhETSims), was to unroll the simulation using a version where all terms are displayed in foreign language. I chose the Indian language of Marathi, because it has such tremendously beautiful script. You can download the Marathi version of “Skate Park Basics” at bit.ly/skaterbarcharts and play with it yourself, but I’ve included a screenshot below:
In the past when I’ve used the Skate Park as an energy introduction, I’ve had students focused entirely on confirming what they already know about “potential and kinetic energy,” and using their idea of “friction” to confirm that “thermal energy” is “created” when object heats up. For example, very few students focused on the crucial observation that the red bar jumps up whenever there is any collision with the track or the ground, so “heating up” ended up being their go-to evidence for energy being dissipated, rather than the other way around.
This year, students were actually focused on making connections to the things we have evidence to describe: changes in height, speed, and banging or sliding that has occurred between objects. The red bar jumping is connected with “impact,” setting the stage for me to blow their minds with the smashing steel balls activity. When the yellow bar isn’t marked as “Total,” students mostly interpreted it as “the starting height” – allowing us to have discussions next class about why the starting height is an indication of total energy in this case. When some students inevitably made the connection to energy (things going up and down in a post-middle school science class will inevitably have this effect, I’ve found…), I got the chance to remind them that those words were “locked” (more on this later), and we didn’t actually yet have any EVIDENCE that we could use agree on that claim. This was quite convincing to them, and may serve as an early experience of success in allowing themselves to free their minds from the science-sounding language they tend to lock themselves into.
Next class, we’ll use the English language version of the simulation to see more complicated elements, like the Eg = 0 reference line, the concept of chemical energy in the fuel in the skater’s jet pack, and maybe even establish a proportional relationship between Eg and mass, height, or g-field. They’ll be relieved to see that their intuition about energy was spot on, but now we’ll be connecting this term to useful connections that already been made to those colored bars.
Here’s a PDF of the handout I used for the lab. Feel free to use it in any way you choose!