Scientific Models for Electrical Polarization
A Close Look at Grade 9 Static Electricity
Why explore the idea of polarization?
A good way to learn about static electricity is by exploring things around us: rub a comb in your hair, peel different fabrics apart, go down a plastic slide in a playground, there's so many possibilities! Another common one is the rubbed balloon sticking to a wall: an example of a charged and uncharged object interacting that requires some subtle science to explain. The grade 6 science curriculum mentions examples like this but leaves out the scientific tools to properly explain it. The grade 9 curriculum mentions charging by induction and again leaves out the science. The missing idea from the curriculum is polarization, a concept that explains the attraction between a charged and neutral object. Polarization also serves as a conceptual bridge between the topics of static and current electricity, which are often taught as two distinct topics. Electrical interactions form the conceptual backbone for an understanding of atoms and molecules, electric circuits and fields, and why those annoying bits of Styrofoam keep sticking to our hands! The curriculum provides a poor road map for learning about electricity; it will pay us great dividends as teachers to do a better job of this, so let's explore polarization! I want to share with you two lessons for grade 9 science that focus on this important electrical concept.
Evidence for polarization
Science starts with observations: we see something unusual that doesn't fit into our understanding. If we've only learned about the “law of electric charges”, we have no simple way to explain this observation experiment: