Diagnostic · Forces, FBDs, N3
Newton's Laws Diagnostic
Maps the force misconceptions behind correct-looking answers — impetus, N = mg, third-law cancellation — module by module, and shows which cluster your class holds.
IB DP · AP · A-Level · GCSE / IGCSE
6 modules
Forms
14 / module
Questions
~15 / module
Minutes
29 clusters
Bands
Run in classrooms at 7 schools · 7 countries · 3 continents
The wrong ideas are not ours. Physics education research has documented them since 1979 — Viennot · Trowbridge & McDermott · Hestenes · Maloney. Every diagnostic is built on them.
“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!”
Dr Tim Short — Physics Teacher, ACS International School Egham
Grade 11 IB · Motion Foundations, Forces & Free-Body Diagrams
What it maps
Six modules. Run only what fits your current unit.
M1
What Is a Force?
Impetus beliefs, inertia-as-force, force/energy/momentum conflation, inanimate contact forces, system boundary errors.
14 questions · 5 clusters · ~15 min
M2
Newton's First & Second Laws
Force–velocity proportionality, acceleration–velocity conflation, "ma" as a force on FBDs, net force errors, inertial frame misconceptions.
14 questions · 5 clusters · ~15 min
M3
Weight, Gravity & Normal Force
Mass–weight confusion, weightlessness myths, N = mg persistence, Newton's third law pairing errors, apparent weight confusion.
14 questions · 5 clusters · ~15 min
M4
Free-Body Diagrams
Missing forces, ghost forces, wrong-object forces, internal/external confusion, friction and tension errors.
14 questions · 5 clusters · ~15 min
M5
Applying Newton's Laws
Friction formula errors, sin/cos decomposition swaps, N = mg on inclines, connected-object constraint errors, axis-choice mistakes.
14 questions · 5 clusters · ~15 min
M6
Newton's Third Law
Third-law pair identification errors, the cancellation trap, unequal effects misconceptions, third law in applied contexts.
14 questions · 4 clusters · ~15 min
A question from it
These aren't gaps in effort. They're systematic misconceptions.
The ghost force after the ball leaves the hand
Ask students to draw a free-body diagram of a ball thrown straight up, just after it leaves the hand. Many will include an upward "force of the throw" that isn't there.
Normal force = mg, always
Ask for the normal force on an incline. Many will write N = mg. On an accelerating elevator floor, the same error appears.
The Newton's third law cancellation trap
Ask whether the weight and normal force on a book are a third-law pair. Many will say yes — and that they cancel.
Constant force means constant velocity
Push a box across the floor at steady speed. Many students conclude the applied force equals the net force — and that force sustains velocity, not acceleration.
How it runs
Shared link. No student logins.
Six modules of 14 questions, about 15 minutes each — run only the module that fits your current unit.
The report arrives within 48 hours of your class finishing.
Request
Request a free pilot for your class
No installs · no student logins · no charge
Reply within 24 hours
Founding-department programme opens January 2027
Pilot request received
Thank you. We'll set up the diagnostic module you selected and email you the link within 24 hours.
Grounded in Hestenes, Arons and Knight