Why Do Secret Decoder Windows Reveal Hidden Messages?

What Crafty Clover says in this video

Intro

Hi there, curious minds! I'm Crafty Clover! Let's discover something amazing. Why do secret decoder windows reveal hidden messages?

The Big Idea

A decoder window is a sheet of red plastic. It lets red light through, so red scribbles seem to vanish into the paper. Dark or green lines look black, so hidden words appear! It is a classic spy trick.

Red Window

Step one: the window is a red filter. It lets red light through and blocks most other colors. Red things look about the same color as the white paper.

Red Scribbles Vanish

Step two: red lines nearly disappear. Red ink and white paper both send red light through the window, so they look nearly the same. The red scribbles seem to fade away.

Dark Words Show

Step three: green or dark lines look black. Their light is blocked by the red plastic, so they stand out as dark. A hidden word suddenly pops out!

A Closer Look

Let's take a closer look! The white paper sends red light through the window. Red scribbles look the same as the paper. The green word looks black. So the red window reveals the secret. With a decoder window, you can make hidden notes for friends.

Quick Facts

Quick facts! Spy toys and puzzle books use this trick. Red plastic passes red light and blocks green and blue. Red lines blend into white paper behind a red window. Never look at the Sun through the window.

Think Like a Scientist

Now, think like a scientist! Write a secret word in green or blue marker on white paper. Cover it with lots of red scribbles. Look through red cellophane. Can you read the hidden word?

Outro

A red window hides red scribbles and shows dark words. Science is amazing! Crafty Clover can be found on Amazon Books, Google Bookstore, and Apple Books. Available for purchase or download! Bye for now!