Turn students into detectives as they decipher encrypted messages.  Introduce your class to modular arithmetic and have a little fun encrypting and decoding secret messages. The activity does not hit many content standards, but...

Now you see them, now you don't! This fun peek-a-boo activity engages young mathematicians in developing their ability to compose and decompose numbers. After being presented with a series of counters, children close their eyes while the...