With the free Formulator Tarsia software from Hermitech Laboratory, (you can download the software and see more information by following the link) it is possible to create
puzzles of various types. These work well with students of any age. Most of the published resources seem to be for students age 11 to 18 but as it is possible to create puzzles, teachers of younger students could create puzzles suitable for their classes.
Note that as well as downloading the application it is possible to download selections of puzzles from Craig Barton and from Bryan Dye. Craig also has a section of his website devoted to Tarsia – note all the ideas here for using Tarsia in the classroom.