Single-problem validation

Table block and hanging mass

1 student taskFull packWorkbench

Table block and hanging mass

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 = (m_2 g - mu_k m_1 g) / (m_1 + m_2) = 2.6 m s^-2" follows from the diagram state and givens.

Focus checkpoints

  • Choose linked positive directions
  • Balance vertical forces on the table block
  • Write kinetic friction on the table block
  • Use the string constraint

Observe for

  • Does the student avoid this trap without prompting: Treating the two masses as if they could have different accelerations.
  • 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 linked positive directionsWhat feature of the diagram, sign convention, or givens makes "Choose linked positive directions" the right next equation?
    Listen for: Choose positive directions along the expected motion for both bodies. The table block moves right and the hanging mass moves downward, so both accelerations can be written as +a.Flag if: Student can only quote "m_1: +x right; m_2: +y downward" without connecting it to the diagram state or givens.
  • Balance vertical forces on the table blockWhat feature of the diagram, sign convention, or givens makes "Balance vertical forces on the table block" the right next equation?
    Listen for: The table block has no vertical acceleration. Its normal force balances its weight, so the friction model can use N = m_1 g.Flag if: Student can only quote "N = m_1 g" without connecting it to the diagram state or givens.
  • Write kinetic friction on the table blockWhat feature of the diagram, sign convention, or givens makes "Write kinetic friction on the table block" the right next equation?
    Listen for: Kinetic friction opposes the table block's rightward motion, so it points left and has magnitude mu_k m_1 g.Flag if: Adding kinetic friction to m_2 g instead of subtracting it from the driving force.; Putting friction on the hanging mass or using mu_k m_2 g for the table friction.
  • Use the string constraintWhat feature of the diagram, sign convention, or givens makes "Use the string constraint" the right next equation?
    Listen for: A light inextensible string over a fixed pulley makes the block's rightward acceleration equal in magnitude to the hanging mass's downward acceleration.Flag if: Treating the two masses as if they could have different accelerations.
  1. Open the Solve-mode link for Table block and hanging mass 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/rough-table-pulley-system 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 linked positive directions".
    • 1Partly correct, but review this row's checkpoint signal: Treating the two masses as if they could have different accelerations.
    • 2Complete row: Axes, sign convention, model constraints, and linked-motion/origin choices are stated.
    Watch: Treating the two masses as if they could have different accelerations.
  • 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 on the table block".
    • 1Partly correct, but review this row's checkpoint signal: Adding kinetic friction to m_2 g instead of subtracting it from the driving force.
    • 2Complete row: Resolved components, force directions, normal/friction setup, or velocity split are correct.
    Watch: Adding kinetic friction to m_2 g instead of subtracting it from the driving force.; Putting friction on the hanging mass or using mu_k m_2 g for the table friction.
  • 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 "Write Newton's second law for each body".
    • 1Partly correct, but review this row's checkpoint signal: evidence reaches "Write Newton's second law for each body" but is not yet consistent across the row
    • 2Complete row: The main Newton's law or motion equation uses the right model, signs, and shared variables.
  • 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 "Eliminate tension and solve for acceleration".
    • 1Partly correct, but review this row's checkpoint signal: Using only m_2 in the denominator after eliminating tension instead of the total mass m_1 + m_2.
    • 2Complete row: The final rearrangement, numeric value, units, and direction/speed interpretation are correct.
    Watch: Using only m_2 in the denominator after eliminating tension instead of the total mass m_1 + m_2.; Using m_2 g as the tension before accounting for the hanging mass's acceleration.

Table block and hanging mass 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.

Table block and hanging mass

Solve modeProblemWorksheetBrief

Focus checkpoints: Choose linked positive directions; Balance vertical forces on the table block; Write kinetic friction on the table block; Use the string constraint

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 linked positive directions". | 1: Partly correct, but review this row's checkpoint signal: Treating the two masses as if they could have different accelerations. | 2: Complete row: Axes, sign convention, model constraints, and linked-motion/origin choices are stated.Watch: Treating the two masses as if they could have different accelerations.
  • 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 on the table block". | 1: Partly correct, but review this row's checkpoint signal: Adding kinetic friction to m_2 g instead of subtracting it from the driving force. | 2: Complete row: Resolved components, force directions, normal/friction setup, or velocity split are correct.Watch: Adding kinetic friction to m_2 g instead of subtracting it from the driving force.; Putting friction on the hanging mass or using mu_k m_2 g for the table friction.
  • 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 "Write Newton's second law for each body". | 1: Partly correct, but review this row's checkpoint signal: evidence reaches "Write Newton's second law for each body" but is not yet consistent across the row | 2: Complete row: The main Newton's law or motion equation uses the right model, signs, and shared variables.
  • Result ___ / 2The final rearrangement, numeric value, units, and direction/speed interpretation are correct.0: No usable evidence for this row, or the work contradicts "Eliminate tension and solve for acceleration". | 1: Partly correct, but review this row's checkpoint signal: Using only m_2 in the denominator after eliminating tension instead of the total mass m_1 + m_2. | 2: Complete row: The final rearrangement, numeric value, units, and direction/speed interpretation are correct.Watch: Using only m_2 in the denominator after eliminating tension instead of the total mass m_1 + m_2.; Using m_2 g as the tension before accounting for the hanging mass's acceleration.