Students wrote secret letter codes by tilting a phone. You can see the movement, but not when the pen was down. Work out what they wrote.
This tests how well you can use incomplete sensor data. Make a predictor, check its guesses and improve them with other students or AI.
Open the game from Project 1
Find the Invisible Ink question in your P1 exam. Open your personal game link. It is only for you.
Prepare before your session
Download 60 examples: 50 are the same for everyone, and 10 are selected for you from a pool of 500. Each includes the code and which movements drew ink. Share examples, code and tools with classmates.
You can enter the waiting room two minutes before a session starts. The countdown updates automatically. Start within the first 40 minutes to get the full 20 minutes.
Ready for Invisible Ink?
Your session starts soon
Start the game when the countdown reaches zero. The 20-minute clock starts when you press Start. You do not need to reload this page.
You can read the rules while you wait.
You will get six motion recordings. You can view or download all six straight away.
First two minutes: guess Drawing 1 only.
Next 18 minutes: submit or change all six guesses. Complete codes save automatically.
After 20 minutes, the form closes. A one-minute grace period lets pending saves arrive. Copy the signed record after that and paste it into P1.
You can use AI, share training files and work with classmates. You will not see the correct answers during a session.
Stage 1
Six hidden drawings
Time remaining
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Six drawings · select any
Drawing 1
Orange = earlier movement. Blue-green = later movement. Moving the cursor does not always leave ink.
Your answers
Valid letters: ACEFHJKMNPRTUVWXY. Codes may not be words. Correct answers are never shown during the challenge.
Complete codes save automatically.
Wait for Saved on the server before you close this page. A partly typed code is not saved.
20:00 · Answers closed
Your time is up. Saving your final answers.
The exam closed at 20 minutes. The server will accept any last save or retry for one more minute. You cannot change your answers now.
01:00
Finalizing your submission…
Your signed record will be ready after the grace period. Keep this page open, or return later to collect it.
Completed
Your answers are saved.
The game saved your first guess and the final six guesses. Correct answers and scores are not shown now. Your score will be calculated offline. No answers or marks are shown now.
Paste this record into the new Invisible Ink P1 question. Press Check, then Save.