The Field Guide
The Mistake Museum
The book behind these diagnostics — 89 of the predictable ways students misunderstand physics, with the exact wording to drop and the one to use instead.
Electrostatics is where a confident vocabulary does the most damage. A student can recite “opposites attract,” put numbers into Coulomb’s law, and read E = F/q off a diagram without ever deciding what attraction actually proves, or whether the field belongs to the source or to the probe. A single-sitting diagnostic that maps the exact misconceptions your students carry across charge, force, the electric field, dipoles, and conductors. Heatmap delivered within 48 hours of class completion.
“Opposites attract,” “the field is the force on a charge,” “E = F/q” are recited detached from their conditions — that attraction is ambiguous, that the field belongs to the source, that the defining ratio does not depend on the test charge. The arithmetic works on routine problems; the model underneath resurfaces in every later topic that leans on the field. These five are the most load-bearing.
A charged rod is brought near a small paper scrap and the scrap jumps to it. Asked whether the scrap is charged, many students say yes — it was attracted, so it must be. But a neutral scrap is pulled in just the same. Attraction is ambiguous; only repulsion requires both objects to carry like charge. This single discrimination is the one the rest of the topic rests on.
A small test charge at a point feels a force. Asked what happens to the field there if the test charge is doubled, many students double the field with it — the field just is the force they measured. But the field is force per unit charge; it belongs to the source and does not change when the probe changes. Reading E = F/q as mere algebra is the second keystone.
Asked what is inside a neutral object, many students say nothing — neutral means no charge. But a neutral object is full of charge held in balance: equal positive and negative. That is why a neutral scrap still responds to a charged rod and why an insulator polarises. Reading neutrality as absence quietly disables induction, polarisation, and induced attraction.
Two equal and opposite charges sit a small distance apart. Asked what they do at a distance, many students cancel them to zero. But a dipole carries zero net charge yet sets up a real field and feels a net force in a non-uniform field — the same reasoning that lets a neutral object be attracted at all. A net-zero system is not an inert one.
Across several items the same habit surfaces: students read the field off the test charge rather than the source — its direction set by the sign of the probe, its value changing when the probe changes, even needing a charge present before the field is “real.” The diagnostic tracks this representational habit as a cross-cutting lens, flagged where it does the most damage to the field keystone.
Thirty items map sixteen bands across charge, force and Coulomb’s law, the electric field, dipoles and polarisation, and conductors. Two bands are the operational core — FOR-1 (attraction versus repulsion) and FLD-2 (field versus force) — and the field bands build on them. Three role-lenses (L1–L3) are surfaced from the option patterns, never scored as standalone bands. Every distractor is a documented student-reasoning pattern, so a wrong answer carries a name, not just a mark.
A body is charged when its positive and negative counts are unequal; charging redistributes existing carriers and creates nothing. Charge is not a fluid that can be made or run out of.
A neutral object holds equal positive and negative charge in balance and still takes part electrically — it polarises and is attracted. Near-keystone.
Rubbing transfers charge rather than creating it, and protons stay bound; the mobile carrier depends on the material — electrons in a solid, ions in solution.
The keystone. Attraction occurs between unlike charges or between a charge and an induced neutral object; only repulsion requires both objects to carry charge of the same sign.
For point or spherical charges the magnitude scales as 1/r² — halving the separation quadruples the force; direction is settled separately from the signs.
The forces on the two charges are equal and opposite however different the charges; the accelerations differ because a = F/m. Bridge to Newton’s laws.
The source sets up a field at every point in space; a test charge reveals it but does not create it. A single-item, lower-confidence band.
The keystone. The field is force per unit charge; the field at a point is not the force on a particular charge, and it belongs to the source, independent of the probe.
The field points away from positive and toward negative source charge; a negative source’s field points inward, not outward. A single-item band.
Each source contributes its own field and the total is the vector sum; in vacuum nothing shields or consumes a contribution — a nearer charge does not use up another’s field.
A field arrow shows direction and strength at a point — not the trajectory a charge will follow. A single-item, lower-confidence band.
A dipole has zero net charge but a real field and feels a net force in a non-uniform field; induced attraction needs no net charge.
Polarisation shifts bound charge slightly; the net charge stays zero, so an attracted or polarised object has not gained charge. Capstone.
The distinction is carrier mobility — free in a conductor, bound in an insulator — not the amount of charge present. A single-item band.
The interior field is zero only at electrostatic equilibrium, as mobile charge redistributes to the surface until it cancels inside; zero field means charges arranged to cancel, not absent.
Grounding is a conducting path to a large reservoir; charging by induction is a definite ordered sequence in which the ground is removed before the inducing charge, and needs no contact.
Naming the charge or the field taken as explaining it. A cross-cutting lens, surfaced from option-level signals and reported as a cohort percentage — never scored as a standalone band.
The field read off the test charge rather than the source — direction, value, or existence tied to the probe. The role-lens most often paired with a flagged FLD-2.
A point-charge or equilibrium result applied where its conditions do not hold. A cross-cutting lens, surfaced from option-level signals.
Within 48 hours of your class completing the diagnostic, we send you a complete misconception analysis — actionable, teacher-readable, and ready to use in your next lesson. Six PDFs per sitting, scored against the 30-question total.
Colour-coded class heatmap showing performance by question and by student performance band (A–D). Items grouped by misconception band so cluster patterns become visible at a glance; folded threads appear as annotations.
Teacher-readable summary: which bands hit hardest, what they mean, the cross-cutting lens readout, and the recommended order of work — for a head of department to act on without re-deriving anything.
A Mistake Museum (21 named exhibits across the 16 bands, the two keystones doubled, plus the three lenses), a parallel Words That Hurt language guide, a sectioned Remediation Worksheet (19 sections), and a Teacher Answer Key — keyed to the bands your class flagged.
What each performance band (A–D) means for your students, with specific teacher action items — from “structurally sound” to “foundations not yet secure,” with the single-item bands explicitly caveated as lower-confidence.
| Q# | Concept Tested | Overall | A (25–30) | B (19–24) | C (13–18) | D (0–12) | Band |
|---|---|---|---|---|---|---|---|
| Q01 | Two perpendicular fields add as vectors | 80% | 100% | 88% | 65% | 54% | FLD-4 |
| Q02 | Polarising an insulator does not make it conduct | 84% | 100% | 92% | 69% | 58% | DIP-2 |
| Q03 | Induced attraction needs no net charge | 64% | 86% | 72% | 49% | 38% | DIP-1 |
| Q04 | A negative source’s field points inward | 48% | 70% | 56% | 33% | 22% | FLD-3 |
| Q05 | Induction is ordered; no contact needed | 72% | 94% | 80% | 57% | 46% | CON-3 |
| Q06 | Zero interior field is not no charges | 72% | 94% | 80% | 57% | 46% | CON-2 |
| Q07 | What a field arrow represents | 76% | 98% | 84% | 61% | 50% | FLD-5 |
| Q08 | Rubbing transfers charge, does not create it | 96% | 100% | 100% | 81% | 70% | CHG-3 |
| Q09 | Equal forces, unequal accelerations | 60% | 82% | 68% | 45% | 34% | FOR-3 |
| Q10 | Neutral has equal positive and negative charge | 72% | 94% | 80% | 57% | 46% | CHG-2 |
| Q11 | E is defined as F/q, not just algebra | 60% | 82% | 68% | 45% | 34% | FLD-2 |
| Q12 | Equal and opposite do not cancel to nothing | 68% | 90% | 76% | 53% | 42% | DIP-1 |
| Q13 | Attraction consistent with the other neutral | 40% | 62% | 48% | 25% | 14% | FOR-1 |
| Q14 | A neutral object still takes part | 88% | 100% | 96% | 73% | 62% | CHG-2 |
| Q15 | The field at a point is not the force | 60% | 82% | 68% | 45% | 34% | FLD-2 |
| Q16 | Attraction does not prove a charge | 44% | 66% | 52% | 29% | 18% | FOR-1 |
| Q17 | Grounding is a path to a reservoir | 60% | 82% | 68% | 45% | 34% | CON-3 |
| Q18 | Charging is a signed imbalance | 76% | 98% | 84% | 61% | 50% | CHG-1 |
| Q19 | Pair forces equal even when charges differ | 52% | 74% | 60% | 37% | 26% | FOR-3 |
| Q20 | A contribution is not used up | 60% | 82% | 68% | 45% | 34% | FLD-4 |
| Q21 | Repulsion is the decisive test | 68% | 90% | 76% | 53% | 42% | FOR-1 |
| Q22 | The mobile carrier depends on the material | 80% | 100% | 88% | 65% | 54% | CHG-3 |
| Q23 | Distance scaling is inverse-square | 76% | 98% | 84% | 61% | 50% | FOR-2 |
| Q24 | Conductor vs insulator is mobility | 64% | 86% | 72% | 49% | 38% | CON-1 |
| Q25 | E is independent of the test charge | 56% | 78% | 64% | 41% | 30% | FLD-2 |
| Q26 | Point-charge law; conditions and sign | 56% | 78% | 64% | 41% | 30% | FOR-2 |
| Q27 | Charge is not a fluid that runs out | 76% | 98% | 84% | 61% | 50% | CHG-1 |
| Q28 | Interior field zero only at equilibrium | 52% | 74% | 60% | 37% | 26% | CON-2 |
| Q29 | A polarised, attracted object is not charged | 76% | 98% | 84% | 61% | 50% | DIP-2 |
| Q30 | A field exists with no test charge | 64% | 86% | 72% | 49% | 38% | FLD-1 |
Q13, Q16, Q21 — Band FOR-1, the attraction-versus-repulsion keystone. Taking attraction as proof of charge sits among the lowest in the diagnostic, at 14% in Band D and 25% in Band C on the hardest item. Until what attraction does and does not prove is settled, the field bands that build on it cannot.
Q11, Q15, Q25 — Band FLD-2, the field-versus-force keystone; Q04 — field direction. The field collapsed into the force, and the single-item field-direction band, fall through Bands C and D — this confusion is not confined to weaker students, and it carries into direction and superposition.
The role-lens (L2); the lower-confidence single-item bands. Submissions that read the field off the test charge rather than the source fire the cross-cutting role-lens, reported as a cohort percentage. The single-item bands (FLD-1, FLD-3, FLD-5, CON-1) are read as directional, lower-confidence signals, never settled.
I carried out a pilot test of the Physics Misconceptions Diagnostics with my Grade 11 (lower 6th) International Baccalaureate classes, as part of their revision for end of year exams. The tests covered Motion Foundations, Forces and Free-Body Diagrams - topics that are fundamental to the IB course as well as A’ level courses.
The tests were all set up by FundaFirst - all I had to do was point the students to web links. The students found the questions easy to access and to carry out. The information that came back from FundaFirst was incredibly useful, identifying areas where the class and/or individuals were weaker. These areas would have been much harder to identify without the tests. FundaFirst then provided concrete examples of how to address the misconceptions, with work sheets targeting these areas.
I will not hesitate to use FundaFirst’s diagnostic testing with future cohorts!
Fill in the form below. The Static Electricity diagnostic suits classes partway through or just past the electrostatics unit, where the charge-and-force reasoning has had time to settle.
→You receive a class-specific diagnostic link and a short setup message you can paste directly to your students. No student logins needed.
→Share the link. The diagnostic takes about 30 minutes (30 questions, no calculator required, single sitting). In-class or take-home.
→Class heatmap, cohort summary, band profiles, and remediation toolkit emailed to you within 48 hours of class completion.
Share your details below and we'll set up the diagnostic link within 24 hours. No commitment — this is a free pilot designed for teacher use and classroom feedback.
The diagnostic is grounded in physics education research, including the work of Arons, Knight, Chabay & Sherwood, and Moore. Our physics content has previously been licensed by Cengage.
The Static Electricity diagnostic is strongest after the FundaFirst kinematics and forces diagnostics — the Coulomb and field items lean on the vocabulary of force, vector addition, and Newton’s third law those diagnostics map. Within the electricity unit it is best run partway through, or just past, the electrostatics material. It runs cleanly on its own too. Six sister diagnostics are also available — Motion, Newton’s Laws, Energy, Momentum, Projectile & Circular, and Oscillations & Waves — same format, same 48-hour turnaround.
View the Motion Diagnostic → View the Newton's Laws Diagnostic → View the Energy Diagnostic → View the Momentum Diagnostic → View the Projectile & Circular Diagnostic → View the Oscillations & Waves Diagnostic →
The book behind these diagnostics — 89 of the predictable ways students misunderstand physics, with the exact wording to drop and the one to use instead.