Self-Contained. I try to include all needed content on the back of the worksheet, or you can run off a classroom set (use colored card stock.) I did this because my STEM classroom didn't have computers (?? odd)
Because they have all needed info, you can use with subs, Classroom, ISS, or with students who return from an absence. Run off a set for everyone, and you can pull them out if your planned activity blows up in your face.
I've created LOTS of Crossword Puzzles. Many of the newer ones have MATCHING or Fill-in-the-Blank options for students who don't want to use the Crossword Grid.
I try to make my worksheets FUN and involve CRITICAL THINKING.