It was the empty terrible feeling in the pit of my stomach at 9:30 at night that really bothered me as I am wading through the stack of papers that I was grading. I had the students do experiments, worksheets, I lectured and there was homework. Some of the students could “do” what I thought was science. They could calculate the answer. They could balance the equation.
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
In this blog post I'll describe a recent attempt at using BCA Tables for teaching stoichiometry. I discuss the method I used with one introductory chemistry class to teach both the algorithm method and BCA tables to learn more about a technique I've been curious about for a while.
Each year we work on specific heat of materials and the heat of fusion of ice. These are two labs that are typical for most chemistry classrooms. Most of the experiments involve a simple calorimetry experiment that uses a styrofoam cup and provides generally good results. There tend to be a couple of key ideas with all of these experiments.
Stoichiometry is arguably one of the most difficult concepts for students to grasp in a general chemistry class. Stoichiometry requires students to synthesize their knowledge of moles, balanced equations and proportional reasoning to describe a process that is too small to see. Many times teachers default to an algorithmic approach to solving stoichiometry problems, which may prevent students from gaining a full conceptual understanding of the reaction they are describing.
Using a whiteboard or poster paper each group of students creates their interpretation of the model thus far based on a content unit they are given.
Bell Ringers related to the Law of Conservation of Matter.
Last year, I worked hard to teach my students how to fail and I believe it was the most important lesson they could have taken away from my class.
As school districts across the country approach the implementation of the Next Generation Science Standards, students will be required to develop models to illustrate what occurs at an atomic level as well as apply various mathematical representations in order to explain a science-based concept. However, what opportunities are we providing our students to allow them to explain what they know about a concept? Students should be provided with regular opportunities to develop and explain concepts, which in turn will allow teachers to formatively assess and address misconceptions.
Larry Dukerich has been using Modeling Instruction for many years. He is a founding member of the AMTA.
