Cipher Wheel

What you need:Cipher Wheel
• Poster board or two small paper plates
• Scissors
• Ruler or compass
• Pencil
• Brass paper fastener
• Ballpoint pen

What you do:
• Cut two circles (1- 6 inches, 1- 4 inches), from poster board. (You can also use two small paper plates.)
• Cut a 1/2-inch-wide V-shape and a 1/2-inch-round window in one circle wheel, as shown.
• Use the pencil to poke a small hole in the center of both wheels.
• Attach the wheels with a brass paper fastener.
• Divide the circles into 26 spaces with a ruler.
• Write the alphabet A to Z on both circles.

Make a second wheel for your friend that matches yours exactly so you can write and decode secret messages.

N.B.: The cipher disk (wheel) was invented in 1467 by Leon Battista Alberti, a famous Italian philosopher and architect.
Alberti used two different alphabets located on concentric rings – this means one ring is inside of or on top of another. By lining up two different letters, one from each ring, he could make a simple substitution alphabet in which he could create a cipher.
For example, if he aligned the A on the outer ring with the G on the inner ring, this would make the following substitution alphabet used to encrypt a message:


From there, he could encrypt his message and send it to someone who knew the secret to revealing the message.

Invisible Ink

Invisible Ink the Baking Soda Way

Mix about 2 TB spoons of baking soda 2 TB spoons of water. Next, write using a Q-tip, toothpick or brush on a piece of paper. Let it dry completely. To read the secret message, paint grape juice across the paper with a paint brush or a sponge. Don’t forget – grape juice stains.
Why it works: Grape juice has an acid that reacts with the baking soda. A different color appears wherever the secret message is written.

Invisible Ink the Milky Way

Put a little milk in a small bowl. Write with the milk on a piece of paper with a Q-tip or a brush. Let your message dry completely. To read the message just heat the paper. Use an iron or 100-watt light bulb or stove element. Don’t rest the paper on the bulb. Ask an adult to help in case a fire starts and never use a halogen light.
Why it works: Milk is an organic product which means it comes from a living thing. When it’s heated, it burns at a slower rate than the paper. Your invisible message shows up brown.

Invisible Ink the Lemon Way

This works the same way as the Milky Way. Simply dab a Q-tip or brush into a bowl of lemon juice and write away. Just make sure you don’t use too much. To see the message, simply heat the paper after it dries. Another way to see the message is put salt on the drying ink. Give it a minute and then wipe the salt off. Use a wax crayon to color over the message.
Why it works: Both lemon juice and milk are mildly acidic and acid weakens paper. The acid remains in the paper after the juice or milk has dried. When the paper is held near heat the acidic parts of the paper burn or turn brown before the rest of the paper does.

Tips: Using the same heat method, you can also use white wine, vinegar, apple juice, and even orange juice, to name just a few. Try some other fruit juices to see what works.


What you need:
• Paper
• #2 pencil
• Clear tape
• Magnifying glass

What you do:
• Rub a pencil on a piece of paper.
• Rub your finger over the graphite.
• Use a piece of tape to remove the graphite from your finger.
• Tape the fingerprint onto a piece of paper.
• Use your magnifying glass to look at your print up close.
• Take the prints of your family and friends and look for the differences!