Aligned Resources

NCTM
Grades 9-12
Numbers and Operations
Understand numbers, ways of representing numbers, relationships among numbers, and number systems

Lessons  •  Activities  •  Show All

Lessons (1)

Clock Arithmetic and Cryptography

Introduces students to modular (clock) arithmetic and how modular arithmetic can be used to encode messages using simple shift, multiple and affine ciphers.

Audiences: Grades 6-8, Grades 9-12

Primary Subjects: Algebra, Discrete, Number and Operations

Related Topics: addition, affine cipher, arithmetic, cipher, cryptography, decipher, division, encrypt, factors, inverse, modular, multiples, multiplication, remainders, shift cipher, subtraction, time

Activities (2)

Screenshot of Clock Arithmetic
Clock Arithmetic

Work with various types of clocks in order to learn about modular arithmetic operations. Parameters: Number of hours on the clock.

Audiences: Grades 3-5, Grades 6-8

Primary Subjects: Discrete, Number and Operations

Related Topics: addition, division, elapsed time, modular, multiplication, remainders, time

Screenshot of Number Base Clocks
Number Base Clocks

Visually explore counting and place value with different number bases, from base 2 to base 16, and up to the hundreds place using a clock like interface. The activity also allows you to look at the numbers on the clock in base 10 or in your other chosen base to explore the relationship between those values.

Audiences: Grades 3-5, Grades 6-8, Grades 9-12

Primary Subjects: Discrete, Number and Operations

Related Topics: arithmetic, counting, exponents, modular