This simple activity was used with Wilson's Fundations program. The cards can be cut and laminated. Students must then decide whether the word is in need of an S or a Z.
The teacher can choose to manipulate this activity however they may desire. I chose to do "Boys" vs "Girls" with a group of six 2nd graders. I handed each group a stack of words and allowed them to decide amongst themselves whether it was an S or a Z that each word needed. We then discussed and reviewed as a group.