Edenix Curriculum  /  Hardware Domain  /  Lesson H-04
Sample Lesson Template

Finding Zero — Coordinate Systems, Calibration & Measurement Error

This is a complete, unedited example of what your teachers receive. Every lesson in all four domains follows exactly this structure.

📄 LESSON OVERVIEW
Domain
Hardware — with Software and Mathematics cross-links
Level
Class 8 – 10  ·  adaptable to ITI Year 1
Duration
80 minutes (double period)
Mode
Demonstration → hands-on measurement → group analysis
Group size
Whole class demo, then groups of 4 – 5 at the machine
Materials
Edenix system · steel rule or vernier caliper (1 per group) · printed worksheet · marker pen · calculator
Alignment
NEP 2020CBSE / NCERTICARAICTE / NSQF
Completed by our curriculum reviewer against your board and syllabus year.
Language
English  ·  हिन्दी  ·  ગુજરાતી

1 Learning Outcomes

By the end of this lesson, a student should be able to:

  • Explain what an origin is, and why a machine cannot move accurately until it knows where zero is
  • Describe the three axes of a Cartesian system and identify them physically on the Edenix frame
  • Predict a coordinate before the machine moves, then measure the actual position reached
  • Calculate the error between predicted and actual position, and express it in millimetres
  • Distinguish between accuracy and repeatability, using their own measured data as evidence
  • Explain in their own words why ±0.5 mm matters when planting a seed

2 Teacher Preparation

The evening before (15 minutes):

  1. Power on the system and run a homing sequence. Confirm all three axes home without a fault.
  2. Clear the bed of plants or obstacles in the area you will use for the exercise.
  3. Place a strip of masking tape along the X rail and mark 0, 200, 400, 600 and 800 mm on it with a marker. This gives students a physical ruler to check against.
  4. Print one worksheet per group.
  5. Pre-load the three test sequences (Test A, Test B, Test C) in the web app, or have the coordinates ready to type.

If the system is not available: this lesson runs almost as well as a paper-and-pencil exercise using the recorded demonstration video, with students measuring from a printed grid. Ask us for the offline variant.

3 Run Sheet

0–10
min
Hook: the blindfold problem Ask a student to close their eyes and point at the classroom door. Then ask them to walk exactly 3 metres towards it. Discuss: what did they need to know that they didn't have? Land on the two answers — where am I starting from, and how long is a metre in steps. This is exactly the machine's problem.
10–20
min
Demonstration: homing Run the homing sequence with the class watching. Narrate it: the machine drives each axis until it detects the hard stop, and calls that position zero. Point out the three axes physically. Introduce the coordinate notation (X, Y, Z).
20–30
min
Predict before you move Give the class a target coordinate. Before running it, each group writes on the worksheet where they think the tool head will end up, marking it on the taped rule. Then run it. Discuss whose prediction was closest and why.
30–55
min
Group measurement rotation Groups rotate to the machine. Each group runs Tests A, B and C, and for each one measures the actual tool-head position with a rule and records it. Every group runs Test A three times — this is the data that will show repeatability.
55–70
min
Calculate and compare Groups complete the error column on the worksheet. Collect all Test A results on the board. The spread across the class is the real teaching moment: the machine returned to almost the same place every time, but the measurements differ. Whose error is that?
70–80
min
Close: why 0.5 mm matters Connect back to farming. A seed hole 5 mm off-centre is survivable. A weeding tool 5 mm off-centre destroys the seedling. Precision is not a specification on a brochure — it is the difference between the tool working and the tool doing harm.

Common misconception to watch for: students routinely conclude the machine is "wrong" when their measured value differs from the commanded value. Push them to ask whether the error is in the machine, in the ruler, or in the person reading the ruler. Most classes discover their own measurement spread is larger than the machine's.

4 Student Worksheet

Printable. Use your browser's print function — the navigation, header and teacher notes are automatically removed and the worksheet starts on a fresh page.

H-04 · Finding Zero

Group:     Date:  

Part 1 — Predict. Before the machine moves, mark where you think the tool head will stop. Target coordinate given by your teacher: X =   mm, Y =   mm.

Our prediction:  

Part 2 — Measure. Run each test and measure where the tool head actually stops.

Test Commanded X (mm) Measured X (mm) Error (mm)
A — run 1
A — run 2
A — run 3
B
C

Part 3 — Think.

a) Your three Test A runs were commanded to the same coordinate. Were the measured values identical?  

b) If they were not identical, list two possible reasons. At least one must be about your measurement, not the machine.

1.  

2.  

c) A seed is 3 mm across. Using your measured errors, would you trust this machine to plant a seed and later weed around it without damaging it? Give evidence from your table.

 

 

5 Assessment Rubric

Criterion Beginning Developing Proficient Advanced
Coordinates Cannot identify the three axes on the machine Identifies axes; unsure how the origin is set Identifies axes and explains homing correctly Explains why a machine origin must be re-established after power loss
Measurement Readings incomplete or units missing Records readings; inconsistent precision Records all readings to the nearest millimetre with units Reads consistently and notes the resolution limit of the instrument used
Error analysis Does not calculate error Calculates error but treats all of it as machine fault Calculates error and identifies at least one measurement-side cause Separates repeatability from accuracy using their own data
Reasoning Answer to Part 3c is unsupported States a conclusion with weak evidence Conclusion supported by the recorded numbers Quantifies the risk to a 3 mm seed and justifies a tolerance
Collaboration Does not participate at the machine Participates when prompted Shares the roles of operating, measuring and recording Coordinates the group and checks others' readings

6 Extension & Differentiation

For students who finish early

  • Repeat Test A ten times and calculate the mean and range. Introduce standard deviation informally.
  • Deliberately loosen a belt (with supervision) and re-run — predict the effect first.
  • Write the coordinate sequence in the web app rather than typing values manually.

For students who need more support

  • Give the commanded values pre-filled so only the measurement column remains.
  • Pair them with a scribe role — reading aloud while a partner records.
  • Use the X axis only. Drop Y and Z entirely for this lesson.

Cross-domain links

  • Software: lesson S-02 builds the same movements as a saved sequence.
  • Farming: lesson F-05 uses these coordinates to lay out a real planting grid.
  • Mathematics: coordinate geometry, ratio, percentage error.

7 Safety

Before any group approaches the machine:

• No hands inside the frame while an axis is moving. Movement is commanded from the app, so a student at the keyboard can start a motion the group at the bed cannot see coming. Agree a verbal call before every run.

• The gantry has pinch points at the rails and the cross-slide. Loose sleeves, dupattas and long hair must be secured.

• Water and mains electricity are both present. Confirm the electronics enclosure is closed and the supply is on an RCD/ELCB before the session.

• Identify the power cut-off with the class at the start of the lesson and confirm every student can reach it.

8 Teacher Notes

This lesson does most of its work through a single reversal: students arrive assuming the machine is the thing being tested, and leave having discovered that their own measurement was the larger source of error. That reversal is worth protecting — resist the urge to correct their readings during the rotation. Let the spread appear on the board.

If the class is strong, the closing discussion can go further: the machine's specification is ±0.5 mm repeatability, but nobody in the room could measure to that resolution with a steel rule. Ask what instrument would be required, and what it would cost. This is a genuine engineering conversation about fitness for purpose.

Typical timing slip is in the rotation. With more than six groups, run Tests B and C as a whole-class demonstration and keep only Test A as a group activity.

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