Particular issues arising and decisions to be made when teaching Electromagnetism

Getting the physics straight

• magnetic forces are action-at-a-distance forces
• domain theory accounts for magnets
• fields as mediating forces
• similarities between electromagnets and magnets

Representing the topic effectively 

• fields are real, to avoid spooky action-at-a-distance
• forces and fields are different kinds of things
• exploiting the similarities between magnets and electromagnets

Particular teaching challenges

• being clear about the status of magnetic fields - what they are
• developing some models with pupils, so that they can reason about the phenomena
• connecting disparate devices back to fundamental physics
• a simple model of force and field
• magnetic fields as representations to reason with
• keeping electrical current and magnetic field separate
• making sense of the iron filing / compass needle patterns

Dealing with existing ideas

• separating out magnetic effects from those due to other forces
• magnetic north and south and the geographic poles are conflated
• bar magnets, electromagnets and geomagnetism are seen as separate 
• action without contact seems impossible

Selected teaching principles

• mini-magnets as an appropriate version of domain theory
• field pattern similarities between electromagnets and magnets
• complex magnetic fields built up from simpler fields
• magnetic fields predict forces
• systematic use of teaching models
• linking ideas from microscopic and macroscopic