## Introduction: Make Your Own Cipher Disk

A cipher is a secret or disguised way of writing- a code. You can make your own code to write in your journal so that no one else can read it or share secret notes with a friend or family member. You don't even have to be in the same house or city, you just both need a cipher disk with the same code on it.

## Supplies

• Paper- any color, card stock will last a bit longer as it's stiffer
• Pencil
• Scissors
• 2 Circles- to trace one slightly smaller than the other
• Brass brad -or- Paper Clip - or- Yarn/String & Tape
• Hole punch -or- you can use your Pencil to poke holes

## Step 1: Make the Circles

Trace your circles & cut them out. We used two different colors of paper so that both parts of the disk stand out but you don't need to.

## Step 2: Punch a Hole

You need to find the middle of your cirlce- you can do so easily by folding it in half one way & then the other to make a + symbol. The middle of the + symbol where the two lines intersect is the middle of your circle. If you have a hole punch you can make a mark there & punch it out.

If you don't have a hold punch you can carefully poke the pencil through to make a hole.SAFETY TIP:Make sure your pencil is fairly sharp so it punches through more easily and make sure your fingers are NOT behind where you're punching the pencil through or you could poke your finger on accident. You can use the edge of a table to help you punch the hole so that you're not poking into the table surface.

Once you have the hole punched into one circle you can mark where the hole goes in the other circle and then punch that one too.

We need the two disks attached together but still able to rotate. To do this you can a brad to the center. Or a paper clip or a bit of string taped on the front and back.

## Step 4: Add the Alphabet

You need to add all of the letters of the alphabet to the smaller circle BUT you have to pay attention to how you do it and use a little math or you'll mess up (like the first photo) and not have enough room.

There are 26 letters in the alphabet. Your circle is already divided into 4 sections from folding it earlier. If you divide 26 by 4 you get 6.5. That means you need 6 letters in two of the sections and 7 letters in the other two sections.

As you write your letters try to keep them as easily spaced as possible. This will make it harder to know how to decode your disk.

## Step 5: Write Your Code

You now need to write your code on the outside disk. First choose what type of code you'll use:

• You can do a simple shift cipher (otherwise known as a Caesar cipher since Julius Caesar used it). For a shift cipher your code is still written in the letters of the alphabet you're just shifting which one's you're using. If you want to use a 3 shift it would work like this: to write an A you'd write a D instead. Each letter of your coded word is written as 3 letters over instead. To make a shift cipher you just start at any letter in the alphabet you want and match that letter up with A. Then just write your ABCs as normal. This may be one of the easier ciphers to share with a friend you won't see face-to-face.
• There are many other types of ciphers using the alphabet letters in different orders. You can look up other ones if you want to find a more complex cipher system.
• You can make a picture cipher where each picture represents a letter. This one is fun but make sure each picture is something very simple that you can draw many times both quickly and small (think the size of a normal ABC letter you would write).

A few things to remember:

• Be careful and remember which letter matches up with A on your smaller disk or you may not be able to decode your letters. If you're worried about remembering which letter matches up with A you can just choose the first letter of your first name as the starting point.
• Check your starting point often to make sure everything is still lined up while your going around your disk.

## Step 6: Write Your Message

Write someone a message and let them decode it with a cipher disk or have them guess what it is without the disk.