National Council of Teachers of Mathematics
Nctm: Figure This: Bar Codes
An exploration of the binary system using U.S. postal zip codes. Discover what numbers the long and short bars in a zip code represent in this one page activity from the NCTM Math Challenges for Families collection.
Math Is Fun
Math Is Fun: Binary Fingers!
Learn how to count in binary using just your fingers and how this skill can help you in arithmetic. Includes a set of practice questions.