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President Jefferson's Cipher: Cracking the Code

Lewis and Clark: The Journey West

Return to Meet the Corps of Discovery: The Members of the Lewis and Clark Expedition


Arts & Humanities

--Language Arts

Social Studies

----U.S. History


  • 3-5
  • 6-8
  • 9-12

Brief Description

Students crack a code for conveying secret messages that President Jefferson gave Lewis and Clark.


Students will
  • figure out the code.
  • decipher messages written with the code.
  • write messages in code.


code, puzzle, secret, Jefferson, Lewis and Clark, Louisiana Purchase

Materials Needed

Lesson Plan

President Thomas Jefferson asked Philadelphia mathematician Robert Patterson to create a code that Lewis and Clark could use to secretly communicate news of the expedition. In this lesson, students decipher "Jefferson's Cipher" and use it to create messages of their own.

Begin the lesson by sharing news of Jefferson's Cipher. According to the Library of Congress,

"A life-long fascination for gadgets and secret codes led Jefferson to present Lewis with this key word cipher developed by Robert Patterson. Lewis was instructed to 'communicate to us, seasonable at intervals, a copy of your journal, notes & observations, of every kind, putting into cipher whatever might do injury if betrayed.' The scheme was never used but the sample message reveals much about Jefferson's expectations for the expedition. The phrase 'I am at the head of the Missouri' reminds us that following the river to its source was an essential part of the president's exploration strategy. 'The Indians so far friendly' was perhaps some brave whistling in the dark, based on Jefferson's hope that his explorers could maintain peaceful relations with native people."

Present students with a copy of the primary source document, Jefferson's Cipher. [Find an easy-to-read copy of the cipher at /a_lesson/images/jefferson_cipher.gif.] Have students use the coded message at the bottom of the cipher ("The man whose mind on virtue bent...") to try to figure out the pattern. Give students 5 to 10 minutes to try to find the pattern. When a student thinks he or she has figured it out, have that student use the code to write your last name. (To make an easy job of correcting students' work, you will have figured out in advance the coded spelling of your last name.) Then let them work at coding their own names.

The code is fairly straightforward. The letters of the alphabet read down the cipher chart. Students will find the first letter of your last name in the left column and then find the corresponding code-letter in the column labeled with the number 1. For the second letter of your last name, students will find that letter in the left column and write the corresponding code-letter found in the column labeled with the number 2. For the third letter of your last name, find that letter in the left column and write the corresponding code-letter found in the column labeled with the number 3 and so on.

While students work on writing codes, gather into small groups students who have not figured out the code. Help them talk through their ideas for cracking the code and help them by providing clues. After everyone has deciphered the code, continue the lesson as follows:

  • Younger students: Provide young students with a piece of paper and direct them to put their names on the paper. Then have them use the Jefferson's Cipher code sheet to write the title of a favorite movie or book in code. When they have completed that assignment, students should hand in the paper and continue with their regular class assignments. Later that day, hand each student one of the coded titles to decipher. (Alternative: Practice using the code in class and have students do this activity as homework.)

IMPORTANT NOTE: For multi-word messages, do not count the first letter of a new word as "1" or "first position." Rather, keep the numbering continuous. If your message has more than 26 letters in total (keep in mind that the cipher table only has 26 columns), the 27th letter (even if it's in the middle of a word) starts the counting over again; that letter would be "1" (first position), and you would continue counting from there.

  • Older students: Let older students get started on the President Jefferson's Cipher work sheet. They will use the code sheet to help them decode Meriwether Lewis's journal entries. As they complete the work sheet, students might write their own coded messages to share with other classmates who have finished the assignment.

Make sure to remind students of the IMPORTANT NOTE above.

ALSO, PLEASE NOTE that the worksheet contains a typo in the last word of line 1 in Code 1. The code reads ndger, but it should read ndgdr. We apologize for the inconvenience.


Answers to President Jefferson's Cipher work sheet.:

CODE 1: Great joy in camp. We are in view of the Ocean, this great Pacific Ocean which we been so long anxious to see.

CODE 2: The roaring or noise made by the waves breaking on the rocky shores (as I suppose) may be heard distinctly.

Lesson Plan Source

Education World

Submitted By

Gary Hopkins

National Standards


NL-ENG.K-12.4 Communication Skills

MATHEMATICS: Problem Solving

GRADES Pre-K - 12
NM-PROB.PK-12.2 Solve Problems That Arise in Mathematics and in Other Contexts


GRADES 5 - 12
NSS-USH.5-12.4 Era 4: Expansion and Reform (1801-1861)

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