As a lesson hook, I would have a coded phrase written on the board and then explain to the children that this is a secret message. Following this hook, I would ask the class to brainstorm all the ways we can send and receive information. For example, brail, text messages, hand signals and flags. After this, I would explain that my secret message and computers have something in common, their own code/language! That computers have systems that encode, process, and transmit information, whether it be a picture or text. An explanation of the binary system would follow, explaining that rather than letters, binary is made up of a series of zeros and ones.
Linking back to the hook, I would inform the students that there is a treasure hidden in the classroom, but the treasure map is in my special code! The students would then receive a worksheet with the coded text along with a key. If the students were an advanced group, only a section of the code would have a key and the students must deduce the rest of the key. This would be a great way to integrate spelling words into the activity, as the students would have to use their knowledge of the word to fill in the gaps. Using the worksheet, the students must use the key (whole or partial) to decode my message and follow the steps to find the treasure (therefore working on their computational thinking as they must decide what data is relevant for decoding, as well as following the steps/sequence to find the treasure).
As an extension/early finishers activity the students could create their own treasure map and code for a fellow student to decode and solve. This could then be used as a literacy prompt for creative writing. Binary could be used as the secret code to focus on the computing aspect, or one could use an original code for creativity! The windings code font on Microsoft Word is an easy way to generate a code.