Become a secret agent as you solve the codes from this fun activity kit for older kids. Find the hidden clues, decode messages, read secret notes and think like a super sleuth doing activities from this Melissa & Doug's kit. Secret Decoder Deluxe Activity Set is the fun way to learn about cryptology - the science of secret messages. This kids first cryptology kit comes complete with 3 activity books (Secret Decoder, Seek & Find, and Secret Message), 2 magic-reveal sticker sheets, 2 decoder wheels, 2 color changing markers, an invisible-ink marker, and a magnifying glass. Think like a secret agent, crack the codes and complete the puzzles to solve dozens of mini mysteries!