This task is not related to CDT but can be good as a one off cover.
Pupils have to use the first letter of their first name and the first letter of their surname to complete the task. If any pupils have any really hard letters (Q, X, Z…) they can pick another easier one. And if pupils have the same 2 letters (EG: Adam Anderson) they can pick a different letter for one of the columns.
Try creating your own version by creating new categories.
Or try to complete the existing categories with another set of letters.