Curated OER
And the Number Is (Second Grade)
Second graders create Mystery Numbers. They give the class clues about the name, value, and multiples of the digits which make up the number.
Curated OER
Clock Arithmetic and Cryptography
Students perform basic operations in modular (clock) arithmetic. Students encode and decode messages using shift and affine ciphers. Students apply their multiplication, division, addition, and subtraction skills.