Place Your First Prop

Share the explorer and companion you imagined after Session 1:

• Your explorer’s name, appearance, personality, and one interest or favorite subject.
• Your companion’s name, kind, personality, and one specialty or interest.
• One thing you eventually want your companion to do: fly, scan rocks, identify animals, find hidden paths, recognize constellations…

It cannot do all of that yet. As you learn more Python, you’ll teach it how.

• ExplorerNovaThe character who explores. You move Nova on the Trail.
• CompanionPixelNova’s small, curious, careful robot friend.
• ToolMoon CompassSomething an explorer uses. Today you place it.
• World objectCrystal LanternSomething that is part of the world. The trail’s destination.

Pixel is in today’s Trail and says hello when you press E nearby. Pixel stays where it was placed: it does not follow Nova or make its own decisions yet.

The Moon Compass is the expedition’s first instrument, and you decide where it lives. The Crystal Lantern is already in the world and marks the end of the trail. Put the compass somewhere an explorer would actually notice it and want to reach on the way.

Mission: create-a-classroom-object

Learning target: Store names, integer x/y coordinates, and a color in variables; explain which values are strings and which are integers; predict an object’s position; then adjust one coordinate from evidence.

object_name = "Moon Compass"
x = 240
y = 180
color = "purple"

• x = 240 means: store the integer value 240 under the variable name x.
• Assignment (=) stores a value under a name.
• Strings are text in quotes: "Moon Compass", "purple".
• Integers are whole numbers with no quotes: 240, 180.

x = 240

x = "240"

Your explorer and companion belong to you, so they live in your own folder, not inside the course folder. From the course folder, run:

python3 make-my-world.py

Open my-explore-world/explorer.py and companion.py. Replace every TODO with concrete choices for your own Explorer and Companion: name, appearance or kind, personality, interest or specialty, and one future_ability. Nova and Pixel are examples, not required answers. The future ability is planning text only. Keep the quotation marks.

explorer_name = "Comet"
looks_like = "a bright orange scarf"
personality = "brave"
favorite_subject = "volcanoes"

MY EXPLORER CARD  (designed by me)
Name:          Comet
Looks like:    a bright orange scarf
Personality:   brave
Interested in: volcanoes

companion_name = "Moss"
companion_kind = "tiny rock turtle"
personality = "patient"
specialty = "finding shiny stones"
future_ability = "light up dark caves"

MY COMPANION CARD  (designed by me)
Name:        Moss
Kind:        tiny rock turtle
Personality: patient
Specialty:   finding shiny stones
PLAN for later, not built yet:
  Someday it will: light up dark caves

Comet and Moss are made-up samples. This card is the new-workspace look. If you set up these files in an earlier class, running them prints your earlier lines instead — both are correct. Either way, your output shows your values.

x and y are integers. A bigger x moves right. A bigger y moves down.

The object file — not starter.py — is what drives the shared world.

You copy the values across yourself. Python does not write or run the object file for you.

Lesson-safe range: x from 80 to 800, y from 100 to 500. This is a classroom visibility guide, not a new rule.

Supported colors — lowercase, exactly as written:

• red
• orange
• yellow
• green
• blue
• purple
• pink
• brown
• gold

Sketch or describe where (240, 180) should appear so an explorer passing through would notice it. Then predict what increasing x by 100 will do — before you change anything.

1. Personalize object_name, x, y, and color in your starter.py.
2. Run the Python file and explain the type of each value.
3. Put the same values in your student-owned file, ../my-explore-world/projects/moon-compass/objects/compass.yaml.
4. Validate your package, then launch the Trail.
5. Checkpoint: show valid: ... and point to the file that drives the world.
6. Observe the position. Close the Trail, change either x or y once, validate, and relaunch. Interact with every world object.
7. Checkpoint: state your prediction, the coordinate you changed, and the movement you observed.

python lessons/sessions/s02/student/starter.py
explore-package validate ../my-explore-world/projects/moon-compass

Then launch the Trail for this mission:

explore-package trail <class packages> ../my-explore-world/projects/moon-compass \
  --player "nova-character:nova" \
  --mission-id "create-a-classroom-object" \
  --name "S02 Place Your First Prop"

If validation fails, fix only the first reported issue and try again.

x: "240"

Explain why this is the wrong type, then repair it without changing the number.

• Color rejected? Use one lowercase name from the supported list.
• Indentation? Use spaces, and line up name, x, y, and color.
• Prop off screen? Return to the lesson-safe range, validate, relaunch.
• Still in the old spot? Close the old Trail, save the object file, validate, relaunch.

Support: keep the sample name and color, and change only one coordinate. Ask your teacher to check your indentation before you retype the file.

Extension: make a second evidence-based coordinate adjustment — after predicting it.

If you ask an AI tool for help, record your intent, your prediction, the exact bounded question you asked, the suggestion you tested, whether you accepted or rejected it, and your own explanation of the change. Do not paste whole files or ask AI for a complete solution.

Read the full discovery →

• Python: What is a variable? Which values were strings? Which were integers? What does changing x do?
• Your world: What are your Explorer’s name, appearance, personality, and interest? What are your Companion’s name, kind, personality, and specialty? What future ability do you want to program later?
• Discovery: What do coordinates describe? How is the fictional Moon Compass different from a real magnetic compass?

Today’s Moon Compass sits where you placed it and does nothing else yet. Next session, it gains its own clue and reveal, becoming an active part of the expedition story.

Save your work in my-explore-world and keep both folders where you can find them next session. Be ready to say which value you changed and what moved because of it — understanding comes before rushing.

What we learned in Python today →