LEARN NC

K–12 teaching and learning · from the UNC School of Education

Vigenere cipher

http://illuminations.nctm.org/LessonDetail.aspx?ID=L618

A lesson plan for Grades 9–12 Algebra 1

Provider: National Council of Teachers of Mathematics

About this resource

Appropriate grades
9–12
Subjects
mathematics (algebra, applied mathematics)
Provider
National Council of Teachers of Mathematics

Legal

Creative Commons License

This catalog record is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License. This license applies to the content of this page only and does not apply to the referenced website.

Students explore the polyalphabetic Vigenere cipher, and encode and decode text using inverse operations. After explaining the Vignere cipher chart, the teacher challenges students to perform a frequency analysis on the ciphertext and determine how they would show someone the method for decoding messages. Illuminations provides detailed instructions, an activity sheet, and a Vigenere grid overhead necessary for completing the lesson.

Students will:

  • Apply the Vigenere cipher in code-making.
  • Compare the Caesar and Vigenere ciphers.
  • Use an inverse process to decode a message.

NCTM Standards and Expectations:

  • Generalize patterns using explicitly defined and recursively defined functions.
  • Develop an understanding of permutations and combinations as counting techniques.

North Carolina Curriculum Alignment

Mathematics (2004)

Grades 9–12 — Algebra 1

  • Goal 1: Number and Operations - The learner will perform operations with numbers and expressions to solve problems.
    • Objective 1.02: Use formulas and algebraic expressions, including iterative and recursive forms, to model and solve problems.