When I discuss nonsense words with my younger students, I introduce them as "silly" words or words that don't make sense. I have been using these sheets to go along with our nonsense/word family centers. The students read the word and if it is a nonsense or "silly" word, they color or dab the silly face. If it is a real word, they color or dab the smiley face.
The students love this activity and I progress from using sheets that only cover one word family to sheets that mix words. These pages can be reused if laminated and white board markers are used, made into a quick assessment, sent home as homework, or used in class any time!