A=1, B=2, C=3 etc. On PP or on paper. Write a number of words and students are to copy them into books.
This can also be done on paper. A nice customisable one can be made quickly with Discovery Puzzle Maker and you can print two to an A4 page. These puzzles require students to decode some words and then they can fill in another set of boxes to make a phrase – I sometimes use it to find the title of the lesson, or to uncover a key phrase/question.
Extensions: translate, write a sentence using words.