Welcome, secret agents and codebreakers! Imagine living in a world where your most important message could be hidden in plain sight – completely invisible until the right trick reveals it. That’s exactly how invisible ink has been used throughout history, from ancient times to modern spy stories. Kings, rebels, and even real-world spies have relied on these clever techniques to secretly pass on confidential information, hidden clues, and covert instructions.

In this activity, you will step into their shoes and learn how to write, hide, and reveal secret messages of your own. Along the way, you will also uncover the science behind why these special inks stay invisible until you know the key to revealing them.