To introduce upper primary to understanding binary and digital text I would make a decoding game for the students to do. I would start with a 3 part process based on the I do, We do, You do.
I do: The teacher does a basic introduction to binary and how coding works. The students will then do activities where they are given a few codes and need to decode the message.
We do: The teacher would create a treasure hunt where the students work in groups of 2. The students are given a decoding sheet. Students will go to the various locations and decode the sheet at the location to find the next location.
You do: Students then create their own code. Students will be asked to make their own code and they will be given to an individual in the class to who they will write a secret message. They will provide that person with the code key they created and the secret code for them to decode.