Diagnostic · SHM, sound, Doppler
Oscillations & Waves Diagnostic
Maps what period, phase, the wave model and the Doppler shift mean to your students, and shows which misreading to address first.
IB DP · AP · A-Level · GCSE / IGCSE
2 (12 + 25)
Forms
37
Questions
12–15 + 28–32
Minutes
19 + lens
Bands
FundaFirst HS diagnostics have run in classrooms at 10 schools · 9 countries · 3 continents
The wrong ideas come from physics education research, which has recorded them since the 1970s: Viennot, Trowbridge & McDermott, Arons, Hestenes, Maloney. The physics comes from Arons, Knight, Moore, and Chabay & Sherwood.
What it maps
Two diagnostics. Run one, or run both.
Oscillations
Simple harmonic motion, phase & resonance
The first layer of oscillations. It finds what students think sets the period, and how they read phase and the sign of the velocity. It also covers the quarter-cycle link between velocity and acceleration, where the small-angle range ends, and driven oscillation.
Covers the period as a property of the system and not of the amplitude, the pendulum’s independence from mass, and the vertical spring’s shifted equilibrium. Also phase and the sign of the velocity, and the quarter-cycle link between velocity and acceleration. Also the small-angle limit beyond which a pendulum is no longer simple harmonic, and driven oscillation and resonance. Six bands, OSC-1A to RES.
12 questions · 6 bands · ~12–15 min
Waves
The wave model, standing waves & the Doppler shift
The wave layer. It finds what students think travels in a wave and what sets its speed. It also covers how they read superposition, standing waves, reflection, energy and the Doppler shift, with a lens on trusting the printed figure.
Covers the nature of a wave and its finite speed, transverse against longitudinal, a snapshot against a history, and wave speed set by the medium. Also sound and superposition, standing waves and their allowed modes, reflection from fixed and free ends, and the open-end boundary. Also energy as amplitude squared, and the Doppler shift. Thirteen bands plus the L-CRIT lens on trusting the figure.
25 questions · 13 bands + lens · ~28–32 min
A question from it
Good marks in oscillations and waves hide these ideas more often than most teachers expect.
A wider swing takes longer
A pendulum is pulled to a larger angle and released. Many students expect a longer period, because a bigger swing should take more time. For small swings the period depends only on the length and on g. The amplitude does not enter at all. Reading the period as a property of the size of the motion, instead of the system, is the first oscillations misconception.
The wave carries the medium along
A pulse runs down a long rope. Asked what travels, many students send the rope along with it, as if the material moved from one end to the other. A wave moves the disturbance and its energy through the medium. Each part of the medium moves in place and returns. The same misreading makes the wave look instantaneous, when its speed is large but finite. What travels is the pattern.
The standing wave travels, slowly
A string driven at resonance shows a standing-wave pattern. Many students read it as a travelling wave moving slowly enough to watch, or picture the nodes drifting along. A standing wave is two equal travelling waves moving in opposite directions, added together. Its nodes and antinodes stay in fixed positions and the pattern does not travel at all. The nodes stay at zero while the points between them oscillate.
The figure must be right
One textbook figure plots the absolute pressure in a sound wave below zero. Another shows a pulse reflecting from a clamped end without inverting. Both are impossible. An absolute pressure cannot go negative, though a pressure variation can, and a fixed-end reflection must invert. Many students accept both, because the figure looks authoritative. The diagnostic tracks this as a lens that fires only when both figures are accepted.
How it runs
Students use one shared link and need no logins.
Two diagnostics. Oscillations has 12 questions in about 12–15 minutes. Waves and Sound has 25 questions in about 28–32 minutes. Run one, or both.
The report arrives within 48 hours of your class finishing.
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Arons and Knight document the misconceptions. Moore and Chabay & Sherwood supply the physics treatment.