What students build
- Horizontal movement
- A controlled jump
- Safe platforms
- Lava collision
- Win and loss states
- Restart logic
Guided Class Project
Guided Class ProjectThe Floor Is Definitely Lava
Cross a room whose floor has become lava for reasons the building manager refuses to explain.
Visible system / hidden curriculum
Build something clear enough to test.
What students learn
- Collision evidence
- Vertical movement
- State during a jump
- Boundaries
- Repeated sensing
- Testing edge cases
What students need
- Browser
- Scratch editor
- Keyboard
- Student-drawn platform map
This is a platformer foundation, not a physics-engine promise. The first version keeps gravity and collision intentionally simple.
Suggested build order
Decisions and checkpoints, not a wall of copied blocks.
Students may use different artwork and implementation details. The shared structure keeps the concept teachable.
- 01
Draw the room
Task: Create clear lava and safe surfaces with strong visual contrast.
Build and test this part before adding the next system.
- Checkpoint
- A student can point to every safe region.
- Likely mistake
- Using similar colours for walls and hazards.
- 02
Add horizontal movement
Task: Change x from keyboard input while checking stage edges.
Build and test this part before adding the next system.
- Checkpoint
- The player moves reliably left and right.
- Likely mistake
- Position changes continue after key release.
- 03
Build a simple jump
Task: Change y upward, then return downward in controlled steps.
Build and test this part before adding the next system.
- Checkpoint
- The jump begins and ends predictably.
- Likely mistake
- Starting another jump while already airborne.
- 04
Sense safe and dangerous contact
Task: Define exactly what counts as platform and lava contact.
Build and test this part before adding the next system.
- Checkpoint
- Each surface produces the intended state.
- Likely mistake
- Transparent costume edges trigger early.
- 05
Add finish and restart
Task: Create a target, win state, loss state, and complete reset.
Build and test this part before adding the next system.
- Checkpoint
- Win and loss cannot happen together.
- Likely mistake
- Only the player position resets.
Test it
Try the edges, not only the easy success.
- Can the player jump forever?
- Can fast movement pass through lava?
- Can the player stand beside a platform?
- Can win and loss overlap?
- Does restart restore jump state?
Common mistakes
Read the clues before changing code.
- Collision is checked only once.
- The player remains marked airborne after landing.
- A platform costume has unexpected collision space.
- Gravity continues after the game ends.
Improve it
Preserve the core system while changing the project.
- Add one moving platform.
- Create a warning tile.
- Add a checkpoint.
- Design a second room with a different coordinate layout.
Challenge levels
Choose meaningful difficulty.
Builder
Add a second safe platform.
Inventor
Create a moving platform with reliable sensing.
Boss Level
Build a second stage and preserve the restart rules.
Show-teacher checkpoint
Demonstrate the working decisions.
- Working movement and jump
- Visible safe and hazard regions
- Reliable loss
- Reliable win
- Complete restart
- One collision bug explained