Using Visual BCA Tables to Teach Limiting Reactants
Looking for a better way to teach stoichiometry? Melissa incorporates modeling into BCA tables.
Looking for a better way to teach stoichiometry? Melissa incorporates modeling into BCA tables.
ChemEd X and the Journal of Chemical Education (JCE) are collaborating to offer a virtual conference like most have never seen before. It is not a webinar. You do not have to schedule specific hours to view a live presentation. I think of it as similar to a virtual book/journal club with the added benefit of having the author leading it. In this case, authors were selected from among those who have published recent articles, activities and research in JCE on the topic of student-centered instruction in chemistry. The theme of this inaugural conference is Chemistry Instruction for the Next Generation.
In an effort to better understand my high school students' knowledge of what is happening during phase changes, heating curve calculations, and the ever popular can crush demo, I run them through a series of activities. First, I ask my students "What Temperature Does Water Boil At?"
Atomsmith works really well on Chromebooks and other platforms. Students can manipulate molecules, add water, do experiments, heat solutions and examine intermolecular forces all on the particulate level. Another nice feature is the "Experiment" section. There are a number of guided activities, usually never more than a page or two. I have found them to be great supplements for activities, experiments and demonstrations.
I started teaching in a chronological order when I began using Modeling Instruction in my classroom. During the second year of "walking in the footprints of the scientists that came before us", I wanted my students to see where they were walking and a colleague and I came up with the idea of making footprints for each of those scientists and posting them on a timeline.
In a previous post I talked about an equation balancing lab that I have been doing with my students involving building molecular models. This time I would like to focus on another lab that I have developed for my model kits.
Here is what I told my students as we were studying gas laws. I have a bag of potato chips at see level and then I go to Denver where the pressure is less? What happens? Draw and build a model on your whiteboard.
A quick search on Amazon for a package of 144 ping pong balls and a trip to the arts and crafts store for paint, magnets, and glue and I was ready to start making my own class set of model kits.
I am a very firm believer that the world of physical science can be visualized and is an excellent medium for teaching students to model and to picture what happens at the molecular level. The first topic we decided to explore was balancing chemical equations. This seems like such a simple topic to chemistry teachers but I have found that it can be quite challenging for many of my inner city students. The first thing they ask me for is a list of rules that they can follow. We can discuss the problems of algorithmic teaching in a later post! For the time being let’s talk about how to get students to understand why they need to balance equations and discuss what we can call “Conservation of Atoms”.
I recently stumbled across a blog about the use of BCA (Before Change After) tables for stoichiometry written by Lowell Thomson. I was thrilled to discover ChemEd Xchange! I wanted to share my journey, spurred on by my students, into the extensive use of the BCA approach in AP and