The 42nd Period | STEM Education Hub

Your teacher will hand you a printed target position-time graph. From this point forward, that graph is the whole assignment — your job is to become the thing the sensor sees, closely enough that your printed result and the target look like they were drawn by the same hand.

🎯 Goals

Break a target position-time graph into segments and describe each one in words before you ever face the sensor.
Translate each segment's slope into a concrete walking pace and direction.
Use live feedback from the motion detector to diagnose and fix specific mismatches.
Explain your final strategy in writing using distance, displacement, speed, and signed velocity — correctly.

🧰 Materials

📡Motion detector / sonic range finder and graphing software (Logger Pro, Pasco, or similar)

📄Your assigned target position-time graph (printed)

📏Meter stick, for calibrating your sense of distance along the track

🖨️Access to a printer, for saving each attempt's graph

📓Physics notebook

DAY 1

Study the Target, Build a Plan

Section 1 of 5

Read Your Target Graph

Mark every point on your target graph where the slope changes.

Each of these points is the boundary between two segments. Label them in order.

For each segment, find the slope, and use it to state a speed and a direction.

This is exactly the skill from Lessons 1-1-2 and 1-1-3 — slope size gives speed, slope sign gives direction, once you know your software's positive direction convention.

⚠️ Confirm your software's sign convention before you plan anything. Guessing wrong here will make every direction in your plan backwards.

Section 2 of 5

Translate the Graph Into a Walking Plan

Use the Strategy Translator below with your own target graph's waypoints.

Enter the (time, position) pairs at each corner of your target graph to get a segment-by-segment plan you can rehearse.

Type in the waypoints from YOUR actual assigned target graph — pairs of (time, position) where the slope changes. This turns your graph into a segment-by-segment walking plan you can rehearse before you ever face the sensor.

Which direction does your software call positive?

Check your software's manual or ask your teacher — most defaults use "away from the sensor" as positive, but don't assume it.

t (s)x (m)

Segment 1 · Walk AWAY from the sensor at 2.00 m/s

0m → 6m over 3s  (Δx = +6m)

Segment 2 · Stand still

6m → 6m over 3s  (Δx = +0m)

Segment 3 · Walk TOWARD the sensor at 1.25 m/s

6m → 1m over 4s  (Δx = -5m)

total distance

11.0 m

total displacement

+1.0 m

total time

10 s

This tool doesn't save your data — copy your segment plan into your notebook before Day 2.

Rehearse the plan on the floor, away from the sensor, using a stopwatch or counted steps.

Pay special attention to the moments where your plan requires a sudden change — stopping instantly, reversing direction, or jumping to a new speed. Those transitions are where real attempts fall apart.

📓 Physics Notebook

Which segment of your target graph do you expect to be hardest to walk accurately, and why? Write your prediction down now, before your first live attempt — you'll check it against what actually happens on Day 2.

DAY 2

Live Attempts and Iteration

Section 3 of 5

Attempt, Compare, Revise

Set up the motion detector and run your first attempt.

Walk your rehearsed plan while the sensor records. Print or save the resulting graph immediately.

Overlay or place your result next to the target graph and find every place they disagree.

For each mismatch, name it precisely: were you too fast, too slow, did you start a segment late, did a corner turn into a curve because you slowed down before turning?

Revise your plan and try again — at least twice more.

Small, specific adjustments (start the second segment half a second earlier, take smaller steps for the slow segment) beat starting over from scratch.

Attempt	Where it mismatched, and why	What you changed next
Attempt 1
Attempt 2
Attempt 3

Fill this in after each Day 2 attempt — it becomes the backbone of your written strategy explanation on Day 3.

DAY 3

Final Attempt and Write-Up

Section 4 of 5

Final Graded Attempt

Run your best, final attempt and print the resulting graph.

This is the graph you'll turn in alongside your target. Choose your strongest attempt if you have more than one from today.

Section 5 of 5

Write Your Strategy Explanation

Write a segment-by-segment explanation of your final strategy.

For each segment: state the target's slope, the speed and direction you walked, and — if it didn't match perfectly — name the mismatch using distance, displacement, speed, or velocity vocabulary, not vague language like "I was off."

Reference your iteration log — what changed between your first and final attempt, and why.

This is where the log you kept on Day 2 becomes the evidence for your write-up.

📊 What Gets Graded

Accuracy — how closely your final graph matches the target's shape
Strategy explanation — correct, specific use of distance/displacement/speed/velocity vocabulary for each segment
Evidence of iteration — your write-up shows what you diagnosed and changed between attempts, not just your final result

📤 Turn In

Your final matched graph printout, alongside the original target graph
Your written, segment-by-segment strategy explanation
Your completed iteration log from Day 2

← Back to Project 1-1-4 OverviewNext up: Lesson 1-2-1, Reading Velocity-Time & Acceleration-Time Graphs.