This is a great activity to get students using the simple present and simple past tense (depending on who they have to make 5 clues about). Students are given one of the 10 famous people featured in the crossword and must come up with 5 clues (not too obvious) about their person. They obviously must keep their famous person a secret from the rest of the class. As an example, the teacher can use Louis Pasteur and give 5 clues to show how it works (e.g. clue number 1 - he came from France). In small classes (less than 10 students) obviously the students can write clues for more than one famous person, and in larger classes they can write the clues in pairs or teams.
My students loved this challenge and it is a great way to get students working independently (I allowed them to research their famous person on the computers first) then as a class (they are all aiming for the same ultimate goal - to complete the same crossword). It is a good way to get them practicing using the simple present (truths) or the simple past (if the person they are giving clues about is now dead).