An intriguing email arrived in my inbox this weekend from ck-12.org. If you aren't familiar with ck-12.org, you should take a look, especially if you teach math or science or coach teachers who do. They offer free resources for teachers to use in order to try to personalize and maximize learning for all students. The email this weekend invited me to check out the Limiting Reactant PLIX. Not sure what that was, so I gave it a whirl.
PLIX is an acronym for Play Learn Interact Explore. This is the latest addition by ck-12, a set of interactive tasks in math and science. They are sorted by discipline. The math topics include algebra, geometry, probability, statistics, analysis, and calculus. The science topics include Earth science, physical science, life science, biology, chemistry, and physics. Each topic has many interactives; I counted 61 for calculus alone!
The lessons within chemistry are numerous and varied. Some are simple and straightforward topics, like accuracy vs precision. Others are challenging abstract concepts, like the atomic emission spectra. What I really liked about the ones I tried was that they are short and sweet: try a couple of interactive tasks and answer a few questions about them.
There were two limiting reactant tasks. One is an activity that asks you to build hot dogs out of buns, sausages, and cheese slices. After you do it, you answer a couple of questions - which reactant was limiting? how many hot dogs did you make? The second task was a particle model. A reaction is provided and you follow the reaction to build product molecules. Similar questions follow. I loved the particle model, but this one is more complicated than the hot dog example. First, the balanced equation and the particle model don't match (C2B should be C2B4). I don't think this is a total deal breaker, but since students need to picture the particles that match the coefficients and subscripts, I would feel compelled to mention this if we were using this PLIX. Or, at the very least, ask the students to find the error. Second, when the products are made, neither reactant is entirely gone. That makes it hard to determine what is limiting, but that might be a good extension of a model building activity my students do in class.
PLIX would be great as a conversation starter in class, as a station in a station rotation, or as a quick homework assignment. They are free, appear to be device-agnostic (I tried laptop and iPad), and interactive with quick formative assessments. I am looking forward to familiarizing myself with more of them, adding them to my repertoire, and watching for them to be polished up when they are no longer in beta.