Home Discussion Unit 3 – option 2 Unit 3 – option 2 By grimmk. Published on August 14, 2022. 0 Some interesting codes used over many years include: morse code and letter number codes. I think morse code is a good one to teach kids at an appropriate age. Share this:TwitterFacebookLike this:Like Loading... + There are no comments Add yours Cancel replyYou must be logged in to post a comment. This site uses Akismet to reduce spam. Learn how your comment data is processed.