SubjectsArts & Humanities
Keywordscode, puzzle, secret, Jefferson, Lewis and Clark, Louisiana Purchase
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 http://www.educationworld.com/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 3and 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:
Answers to President Jefferson's Cipher work sheet.:
Lesson Plan Source
LANGUAGE ARTS: English
NL-ENG.K-12.4 Communication Skills
NM-PROB.PK-12.2 Solve Problems That Arise in Mathematics and in Other Contexts
NSS-USH.5-12.4 Era 4: Expansion and Reform (1801-1861)