VOLCANO ISLAND
Lava Trail Backtracker
A lava wall blocks the island trail! Teach the explorer to remember every choice, undo a dead end, and try a new path.
🧠 Before we start
At the Koi Garden, your program remembered its current state. Now it will remember a whole trail of choices. When a path fails, it undoes the newest choice and tries another. Programmers call this backtracking.
👣 Try→🧠 Remember→↩️ Undo if stuck→✨ Try another
Challenge 1 of 4Build the backtracking recipe
1
Arrange the trail recipe
Tap four visual instruction blocks in the order a backtracking program uses them.
MY VISUAL BACKTRACKING PROGRAM
1 · TRY
2 · REMEMBER
3 · CHECK
4 · UNDO
What does the explorer do before a choice can be remembered?
2
Escape the lava maze
Try the ash trail first. It ends at lava, so undo each newest trail mark. Then try the palm trail.
VOLCANO TRAIL MAP
Trail memory: CAMP
Start by trying the ash trail. The program will remember each choice.
3
Unwind the memory pile
The newest choice sits on top. Tap the trail cards from newest to oldest, just like a backtracking program.
NEWEST CHOICE — UNDO THIS FIRST
Which choice was added last?
4
Debug the stuck explorer
This routine sees a dead end but keeps the bad choice in memory. Tap the pulsing bug, then add the missing action.
👣 Try one path
🧠 Remember the choice
🚧 Notice a dead end
Find why the explorer cannot try a different path.
🌟 What you learned
- Backtracking tries one choice at a time.
- The program remembers every choice in its current trail.
- A dead end means the newest choice must be undone.
- After going back, the program can try a different choice.
- This idea helps programs solve mazes, puzzles, and matching games.