When I used this type of activity in a center at least once a week, my students' spelling abilities improved dramatically in a short time. This activity works especially well when you allow students to work together with partners. Usually I have them spend about 20 minutes trying to find words on their own, and then I let them work with a partner to continue to find more words.
Just be aware that if you let your students take it home, they may get a little too much "help" with this! It's fun for the whole family! You can download it from my TeachersPayTeachers store or my Seasonal Page on Teaching Resources.