Textbook+Analysis

Textbook Analysis for Rates of Change (CURRENT) I. How is current developed and used throughout the text?

CJ – Begin with electrostatics (charged objects and electric force between point charges, conductors and insulators, charging by contact and induction). Next comes electric fields and potential, then ohm’s law (voltage, resistance, current in simple circuits), power, then finally more complex electric circuits (series and parallel).

Conceptual Physics goes in the same order. Both texts use the water flow analogy.

Physics by Inquiry – designed more for pre-service teachers to help them understand the content they’re teaching. Mostly has experiments with circuits, but no formal explanation of electrostatics.

II. Where does it appear in the content?

Electricity is usually taught at the end of the course, after mechanics, light and waves. It can occasionally be taught as the first topic after mechanics, heat and thermo. Magnetism is usually the first topic that follows Electricity. It’s important for students to have a decent understanding of energy transformation and the different forms it can take. III. How might the organization of rate of change throughout the text influence: a) Current

Most students don’t think of current as a rate of //change//. They don’t think it’s changing over time…they see the relationship between V, I, and R, but current isn’t developed on its own as a rate, speed of electrons. Hard to see that current from the battery is changing (depending on the resistance and the voltage).

What is it that’s moving? Students get hung up on the idea of voltage

b) the larger discipline of math or science?

IV. What are the similarities and differences between textbooks?

-depth of mathematical explanation - depth of conceptual explanation - different analogies that are used (gravitational potential vs. water in a pipe pushed by a pump). - Physics by inquiry presents circuits first, then current and voltage. - difference in amount of connection between current, past and upcoming topics.

V. How is this analysis influencing…

a) your team’s understanding of current

- We need to do more research into students prior conceptions about current and electricity. - We’d like to understand voltage and potential difference better, in addition to what’s actually happening inside a circuit (what’s flowing? If current is a rate of flow of electrons, what does more current mean?). - Concept map to determine the various relationships between ideas in electricity. - What do students need to know about current? Why? What are the big ideas that they should take away? -ratio reasoning…when talking about rates, need to understand the compound nature of the units (Coulombs per second, meters per second, etc.)

b) your view of what students should understand before learning about rates of change