Magnetism at three levels of expertise

Francis Stefani completed a PhD in science education with Jill Marshall two years ago and is currently a research scientist at Pickle Research Campus. Prior beginning his PhD Francis worked in a plasma lab where he discovered that the plasma scientists had very different ways of thinking about magnetic fields than he had learned in his physics courses. This lead Francis to decide to study how people at various levels of expertise think qualitatively about magnetism and the ways they use mathematical and pictorial models to solve problems.

The Study

• A written test of 7 non-standard questions concerning magnetism. These questions were designed to be non-standard question that should be solvable by excellent students after a first course in E&M (this was checked with Roger Bengtson and Dan Heinzen who had just taught intro E&M when the test was developed).
• The test was administered to 10 subjects in each category: novices (UT students who had completed one semester of E&M for physicists or engineers), experts-in-training (EITs) (advanced undergrads and graduate students who had at least 1 upper division course in E&M) and experts (professors or researchers at national labs)
• A subset of each category also participated in an oral interview after the written test.
• Interviews were conducted with experts first then EITs and finally novices in order to fine tune the interview questions before interviewing the group with the most misconceptions.
• Interviews were transcribed (700 pages total) and fed into the program ATLAS.ti to facilitate easy tagging and searching of key phrases (coding in the parlance of education research)
• Several different key phrases were analyzed to try to identify mental models being used and to allow Francis to sort subjects in a meaningful way.
  
  

Novices

• Confused demos they had seen in class (Ex. dropping magnet through a metal tube vs. metal ring sitting on a metal tube with coils inside that get sudden current flowing through them causing ring to jump). On the positive side students did recognize themselves that they were confused.
• Often over-generalized things they had learned. Novices took special cases and treated them as general cases (Ex. an infinite solenoid has no field outside the solenoid, novices also said finite solenoids have no field outside)
• Novices used Fundamental Mental Models that involved latching on to one small piece they had seen previously but did not full understand (latch onto a lab, demo, textbook picture etc.)
  
  

EITs

• Very careful about their word choice not wanting to say anything wrong.
• Drew on several different concepts when solving problems. Their knowledge was much less fragmented than novices.
• Integrated math and physics concepts in their answers.
• Answers were generally correct but were very long. EITs solved problems by “brute force”.
  
  

Experts

• Much more relaxed and colloquial in their interviews than EITs.
• Fairly short, elegant solutions that they would elaborate on when asked.
• Mathematical knowledge and conceptually knowledge completed integrated an inseparable.
  
  

Implications for Instruction

• E&M should be taught in a more holistic way emphasizing connections between concepts and using E & B fields as unifying concepts. (This is general idea of many current E&M reforms)
• Need to give students a variety of experiences (integrate and connect labs, demos, discussions, simulations) for them to later recall during problem solving to avoid them latching on to incomplete concepts.
• Don’t focus solely on idealized situations which makes students over generalize.
• Make students do modeling. (Both in terms of Fermi type problems Eric Mazur talked about and computer modeling like in Matter & Interactions curriculum)
• MIT is doing some interesting things with visualizations in TEAL but there is evidence that students need to engage with the material through simulations they control rather than passively observe visualizations that they have no control over.