The CASTLE™ Approach
CASTLE (Capacitor-Aided System for Teaching and Learning Electricity) is a high school electricity curriculum that leads students from initial naive ideas to an increasingly expert understanding of electrical phenomena. A sequence of self-guided experiments uses large capacitors and transient bulb lighting to help students confront their misconceptions, grasp the physics of current propulsion and build intuitive explanatory models.
The core experiments stimulate students to model mobile charge as a compressible fluid and electric potential as “pressure” in the fluid. They learn that a pressure difference is what makes charge move through a resistor. The advanced experiments reveal two kinds of charge and distant action, which suggests modeling fields as pressure raising/lowering “halos” around ± charges. Connections between the electron, the atom and mobile charge in circuits are also explored.
CASTLE instruction gives priority to development of qualitative reasoning skills. No prior knowledge of electricity is required, making the curriculum accessible to students in all levels of high school physics. And sections have been redesigned to facilitate beginning the CASTLE curriculum in 8th or 9th grade.
- 25,000 µF Capacitor — Provides the foundation for this intuitive introduction to current electricity.
- Wires with Alligator Clips — Ten color-differentiated wires make circuit connections quick and easy — no soldering or wire twisting.
- Battery Holder — Securely holds batteries and yet makes them very visible so that their function within the circuit is evident.
- Miniature Light Bulbs — Differently shaped bulbs have different resistance values.
- Curriculum Guide Download (pdf) — Contains a teacher’s manual (pdf) with comprehensive background information and a student manual (pdf) for printing and distributing in class. Sections may be printed individually as needed.