Single-problem validation

Crate pulled across a rough floor

1 student taskFull packWorkbench

Crate pulled across a rough floor

Run one observed attempt for this mechanics model before changing problem scope.

Full validation pack
  1. Run one student on one problem at a time; do not demo the full site first.
  2. Start from the public problem page, then switch to Solve mode before any answer-key exposure.
  3. Record attempt time, finish state, first hesitation checkpoint, first wrong path, and whether the reveal changes their explanation.
  4. Paste the copied Solve-mode attempt snapshot into notes as evidence, but do not treat it as a score or success verdict.
  5. Count the visible corrections or checker recoveries before the student can explain the governing equation in their own words.
  6. Record the exact first-success quote or mark no usable evidence; do not infer clarity from a correct final answer.
  7. Show the tutor the worksheet answer key only after the student attempt, then capture concrete reuse or rejection reasons.

Decision gate

Student task

Solve modeProblemWorksheet

Student can explain why "a = [P cos(theta) - mu_k(mg - P sin(theta))] / m = 2.9 m s^-2" follows from the diagram state and givens.

Focus checkpoints

  • Choose horizontal and vertical axes
  • Balance vertical forces
  • Write kinetic friction from the reduced normal force
  • Apply Newton's second law horizontally

Observe for

  • Does the student avoid this trap without prompting: Using N = mg and ignoring that the angled pull reduces the normal force.
  • Which checkpoint caused the first real hesitation or correction?
  • Did the reveal help them explain the equation, or only copy the next algebra line?

Equation-choice spot checks

  • Choose horizontal and vertical axesWhat feature of the diagram, sign convention, or givens makes "Choose horizontal and vertical axes" the right next equation?
    Listen for: The crate accelerates horizontally, so standard horizontal and vertical axes keep the motion equation direct.Flag if: Student can only quote "+x = right, +y = upward" without connecting it to the diagram state or givens.
  • Balance vertical forcesWhat feature of the diagram, sign convention, or givens makes "Balance vertical forces" the right next equation?
    Listen for: The crate has no vertical acceleration. The upward rope component helps support the crate, so the floor supplies less normal force than mg.Flag if: Using N = mg and ignoring that the angled pull reduces the normal force.; Swapping the pull components by using P sin(theta) horizontally and P cos(theta) vertically.
  • Write kinetic friction from the reduced normal forceWhat feature of the diagram, sign convention, or givens makes "Write kinetic friction from the reduced normal force" the right next equation?
    Listen for: Kinetic friction is proportional to the normal force, and here the normal force is reduced by the upward component of the pull.Flag if: Using static-friction threshold logic after the problem states the crate is sliding.
  • Apply Newton's second law horizontallyWhat feature of the diagram, sign convention, or givens makes "Apply Newton's second law horizontally" the right next equation?
    Listen for: The horizontal component of the pull drives the crate right. Kinetic friction acts left and must be subtracted.Flag if: Adding friction to the pulling force instead of subtracting it.
  1. Open the Solve-mode link for Crate pulled across a rough floor and ask the student to restate the target unknown before writing equations.
  2. Ask for the diagram state first: axes, direction assumptions, and the force or motion components they expect to use.
  3. Let the student attempt one scratch line before any checkpoint reveal, then use Check this line only after the attempt.
  4. If they stall, reveal one checkpoint and ask them to say which diagram element or given made that equation necessary.
  5. After the result checkpoint, ask for one sentence explaining why the chosen governing equation was the right model.

Tutor review prompts

  • Would you send /problems/angled-pull-crate-friction to a student stuck on this exact problem?
  • Which checkpoint would save you the most explanation time?
  • Which diagram label, assumption, or rubric row feels misleading or too thin?
  • What one change would make this problem page worth reusing in a lesson?

Tutor rubric cues

  • Setup (0 / 1 / 2)Axes, sign convention, model constraints, and linked-motion/origin choices are stated.Score descriptions
    • 0No usable evidence for this row, or the work contradicts "Choose horizontal and vertical axes".
    • 1Partly correct, but review this row's checkpoint signal: evidence reaches "Choose horizontal and vertical axes" but is not yet consistent across the row
    • 2Complete row: Axes, sign convention, model constraints, and linked-motion/origin choices are stated.
  • Components (0 / 1 / 2)Resolved components, force directions, normal/friction setup, or velocity split are correct.Score descriptions
    • 0No usable evidence for this row, or the work contradicts "Balance vertical forces".
    • 1Partly correct, but review this row's checkpoint signal: Using N = mg and ignoring that the angled pull reduces the normal force.
    • 2Complete row: Resolved components, force directions, normal/friction setup, or velocity split are correct.
    Watch: Using N = mg and ignoring that the angled pull reduces the normal force.; Swapping the pull components by using P sin(theta) horizontally and P cos(theta) vertically.
  • Net-force / governing equation (0 / 1 / 2)The main Newton's law or motion equation uses the right model, signs, and shared variables.Score descriptions
    • 0No usable evidence for this row, or the work contradicts "Apply Newton's second law horizontally".
    • 1Partly correct, but review this row's checkpoint signal: Adding friction to the pulling force instead of subtracting it.
    • 2Complete row: The main Newton's law or motion equation uses the right model, signs, and shared variables.
    Watch: Adding friction to the pulling force instead of subtracting it.
  • Result (0 / 1 / 2)The final rearrangement, numeric value, units, and direction/speed interpretation are correct.Score descriptions
    • 0No usable evidence for this row, or the work contradicts "Divide by mass and calculate acceleration".
    • 1Partly correct, but review this row's checkpoint signal: Putting ma in the vertical equation even though the acceleration is horizontal.
    • 2Complete row: The final rearrangement, numeric value, units, and direction/speed interpretation are correct.
    Watch: Putting ma in the vertical equation even though the acceleration is horizontal.; Reporting the net force without dividing by mass.

Crate pulled across a rough floor session notes

Capture observed outcomes from real attempts: time, hesitation checkpoint, wrong path, copied Solve-mode snapshot evidence, recovery, equation-choice explanation, first-success evidence, manual tutor row scores, and tutor send-link decision.

Next-fix queue

Use after real attempts: carry only observed time, hesitation, wrong-path, recovery, equation-choice, first-success, manual tutor row-score, or tutor-rejection evidence into the next product slice. The evidence gate flags partial notes before they masquerade as product signals.

No observed attempts yet
Observed sessions: 0Ready for next-fix review: 0Need more observed evidence: 0

Run one single-problem Solve-mode attempt before choosing a product fix or adding another mechanics model.

No observed next fixes yet.

Crate pulled across a rough floor

Solve modeProblemWorksheetBrief

Focus checkpoints: Choose horizontal and vertical axes; Balance vertical forces; Write kinetic friction from the reduced normal force; Apply Newton's second law horizontally

Tutor row-score template: Setup ___ / 2; Components ___ / 2; Net-force / governing equation ___ / 2; Result ___ / 2; reteach cue: ___

Seed from Solve snapshotPaste a copied Solve-mode attempt snapshot. Only filled starter fields are imported; placeholder blanks stay missing evidence.
Evidence checklistNeed all five evidence groups before this note can drive next-fix review.
  • Missingattempt time / finish stateAttempt time and finish state
  • Missingequation-choice evidenceEquation-choice explanation
  • Missingfirst-success quote or verdictFirst success-test evidence
  • Missingscratch, checker, or reveal evidenceWrong path or scratch line / Solve attempt snapshot evidence / Corrections before recovery / Reveal outcome
  • Missingmanual tutor row, tutor decision, or next-fix cueTutor row scores and reteach cue / Tutor send-link decision / Next fix before adding problems
Manual row-score summaryEnter observed 0/1/2 row scores to summarize manual tutor evidence.Blank row-score starters stay out of totals and do not count as grading.
Manual row-score helper0/1/2 rows from the existing tutor rubric. Blank starters do not count as evidence.
  • Setup ___ / 2Axes, sign convention, model constraints, and linked-motion/origin choices are stated.0: No usable evidence for this row, or the work contradicts "Choose horizontal and vertical axes". | 1: Partly correct, but review this row's checkpoint signal: evidence reaches "Choose horizontal and vertical axes" but is not yet consistent across the row | 2: Complete row: Axes, sign convention, model constraints, and linked-motion/origin choices are stated.
  • Components ___ / 2Resolved components, force directions, normal/friction setup, or velocity split are correct.0: No usable evidence for this row, or the work contradicts "Balance vertical forces". | 1: Partly correct, but review this row's checkpoint signal: Using N = mg and ignoring that the angled pull reduces the normal force. | 2: Complete row: Resolved components, force directions, normal/friction setup, or velocity split are correct.Watch: Using N = mg and ignoring that the angled pull reduces the normal force.; Swapping the pull components by using P sin(theta) horizontally and P cos(theta) vertically.
  • Net-force / governing equation ___ / 2The main Newton's law or motion equation uses the right model, signs, and shared variables.0: No usable evidence for this row, or the work contradicts "Apply Newton's second law horizontally". | 1: Partly correct, but review this row's checkpoint signal: Adding friction to the pulling force instead of subtracting it. | 2: Complete row: The main Newton's law or motion equation uses the right model, signs, and shared variables.Watch: Adding friction to the pulling force instead of subtracting it.
  • Result ___ / 2The final rearrangement, numeric value, units, and direction/speed interpretation are correct.0: No usable evidence for this row, or the work contradicts "Divide by mass and calculate acceleration". | 1: Partly correct, but review this row's checkpoint signal: Putting ma in the vertical equation even though the acceleration is horizontal. | 2: Complete row: The final rearrangement, numeric value, units, and direction/speed interpretation are correct.Watch: Putting ma in the vertical equation even though the acceleration is horizontal.; Reporting the net force without dividing by mass.