Students explore codes, decode secret messages, and create codes of their own to use with their friends. They examine the use of gestures, letters, symbols and numbers in codes.

Students rewrite word problems using expressions and equations. In this algebra lesson, students use the correct variable to solve and write equations. They use the TI to graph their solution.

Seventh graders, in an introductory algebra class, code and decode messages using substitution ciphers. Role-playing as mathematicians, they work in groups to decipher several messages, one of which translates to "math is awesome."

Students solve matrices by multiplication. In this algebra lesson, students create coded messages and relate it to solving matrices. They multiply and find the inverse of matrices.

Pupils perform basic operations in modular (clock) arithmetic. Students encode and decode messages using shift and affine ciphers. Pupils apply their multiplication, division, addition, and subtraction skills.