Go Fish Challenge kids to a rousing game of cards . and sneak in some irregular plural noun matching practice while playing! Free printable game cards (mouse/mice, leaf/leaves, man/men, etc.) at Relentlessly Fun, Deceptively Educational.
This is a cheap and simple way to practice plurals with students: write the noun on the sentence strip, fold the right hand corner to cover up whatever gets taken away on the reform of the word, then write the new ending that makes the word plural.