The possiblity for in class activities related to data representation is endless. In school a very popular activity was to encode and decode ‘ciphers’.
In pairs, students are enaged to create their own ‘cipher’. They can be as creative or as simple as they’d like. Once the students are formulated a ‘key’ each student will write a message in their  code. Students can then trade papers and they will try to decode each other’s messages.