Start your sleuths off by having them write simple messages in encrypted codes. To begin, guide your students through the creation of a code by having them write the alphabet in colored ink on a sheet of paper. Next, instruct each student to select a random spot in the alphabet he already wrote and start the alphabet again below this first letter, using a different colored ink this time. Upon completing this task, he should have a two-rowed alphabet in which each letter is connected to another. Instruct students to write short messages in this code they have created, using the second letter to stand for the first. Allow students to pass their papers and their created codes to classmates and have them decode the secret phrase.
For a more artistic option, try a picture code with your students. Start again by having students write out the alphabet on a sheet of paper, then below each letter ask students to draw pictures to represent them. For example, a student could draw a heart under the A to stand for this letter and so forth. Ask students to compose new messages using these pictures and again trade and decode.
To tie this activity into math, make the code a numeric one. Ask students to assign each letter of the alphabet a different number. This number could relate to the letter’s position within the alphabet, or the students could randomly assign the numbers. Have students write out codes in numbers for their peers to decode. For more advanced students, ask them to write mathematical equations to relate to each number instead of the number itself. For example, the student could write 30/3 to point to the letter B, which they have paired with number 10.
Fascinate your students with a simple invisible ink activity. To start the activity, arm each student with a sheet of paper, a cotton swab and a bowl of lemon juice. Ask students to write messages with the lemon juice by dipping the cotton swab and writing with it. Allow these messages to dry. Next, trade the papers among the students. Help students use a hairdryer or iron to heat the paper, a process that will turn the lemon juice black and reveal the message.