Dr. Stone needs a detective. Turn your sound on.

Lessons you need for this case

The six notes in this case use five secret codes. You must have finished all five code lessons to solve the whole mystery. If you skipped one, go back and learn it now.

Check the box next to each lesson you have finished.

    Check all five lessons to open the case.

    How this case works

    1. Read about the case and meet the eight suspects.
    2. Crack the six notes. Nobody will tell you which code is which, and one of the notes holds the secret word you need for two of the others.
    3. Answer three questions. Who is letting the penguins out? Where do the penguins go? Why was it kept a secret?

    Be careful with step 3. A wrong answer locks the answer box for 3 minutes. Guessing will not work. Cracking the notes will.

    My badges

    Your work saves on this computer.

    Teacher note

    Answers are inside. Enter the teacher password.

    What is going on

    The Copper City Zoo has twelve penguins. Every evening at 6:00, Keeper Sam shuts their gate. Every morning this week, all twelve have been found waddling around the zoo.

    On Monday they were in the gift shop. On Tuesday they were riding the zoo train. On Wednesday they were splashing in the fountain. Nobody has seen how they get out.

    The zoo director, Dr. Stone, is not laughing. She has a rule: any animal that gets out by itself three times is too much trouble, and it is sent away to another zoo. She has hired you to find out who keeps opening that gate.

    What we know

    The gateIt is not broken. It has no lock and no key. It has a simple latch that lifts up.
    The penguinsEvery morning all twelve are found safe. And here is something odd. None of them are hungry at breakfast.
    The cameraIt points at the visitor path, not at the gate. Nobody thought the gate needed watching.
    The notesSix notes with strange writing, found around the penguin pool. All six are in the same pen.
    FREETHEM
    A stickerA FREE THEM sticker was found stuck on the gate. The stickers come from Willow Banks and her club.

    Dr. Stone says: "It is the sticker girl. Willow. If a person is opening that gate, catch her. If the penguins are doing it by themselves, well, you know my rule."

    The timeline

    • Three weeks ago. Keeper Sam starts coming to work very early, before the sun is up. He says he likes the quiet.
    • Monday. All twelve penguins are found in the gift shop. One is wearing a hat.
    • Tuesday. All twelve are found riding the zoo train.
    • Wednesday. All twelve are found in the fountain by the front gate.
    • Thursday. Dr. Stone hires you. She reminds everybody about her rule.
    A word to know: latch. A latch is a small bar that holds a gate shut. You lift it to open the gate. It is not a lock, and it does not need a key.

    Eight names are on the list

    Each of them has a reason, or was near the gate. An alibi is proof that you were somewhere else when it happened. Look at who has one.

    Dr. Stone says: "Eight? I count seven suspects and one bird. Somebody put a penguin on my list as a joke. Very funny. Now find Willow."

    The six notes

    Every note has a secret message. First work out which code it is. Then crack it. The keys are in the Code toolkit tab. You need all six notes to answer who, where, and why.

    Notes cracked: 0 of 6

    Caesar Wheel Review the lesson

    Every letter slides the same number of steps down the alphabet. Find the secret number, then slide the strip. Look up each code letter on the top row. The real letter is right under it.


    Spartan Scytale Review the lesson

    The letters are not changed. They are only mixed up. The message was written on a strip of paper wrapped around a rod. Wrap the strip around a rod of the same size and the words line up again.


    Read across each row, starting at the top. If the rod is the wrong size, you get nonsense.

    Tap Code Review the lesson

    Every letter is two sets of taps. Count the first set to find the row. Count the second set to find the column. C and K share a box.

    Two taps, then three taps, means row 2, column 3. That is the letter H.

    Book Cipher Review the lesson

    The code is a list of number pairs. You cannot read it without the right book, page, or sign. In this case, the first number is the line. The second number is the word in that line, counting from the left. Write down each word you land on.

    No book, no message. Think about where the note was found.

    Keyword Cipher Review the lesson

    Write the secret word first. Then write the rest of the alphabet after it, skipping any letter the word already used. That is the code alphabet. Type the secret word here and the strip builds itself. Look up each code letter on the top row. The real letter is right under it.

    No secret word yet? Count the letters.

    In English, E shows up more than any other letter. T and A are next. The letter that shows up most in a coded note is a good guess for E.