I remind my kids to think if the apostrophe works as a band aid or a lasso. If it doesn't, it's not needed.
I don't claim the band aid story. My students gave it to me, but it
I do claim the lasso story as my own. When teaching possessives, I make sure the kids know the word "possess" means to own or have something. I'll get into stories of rodeos, telling them how cowboys throw their lasso and claim their cattle. I show them pictures I've googled of cowboys and lassos. In a possessive, the noun with the 's owns the following item. I even get into turning the apostrophe into a lasso and circling the next word. They practice this on their whiteboards (I'm a whiteboard fanatic!) and love to draw the lassos.
Naturally, if the word they're thinking about doesn't need a band aid or a lasso, they shouldn't be using an apostrophe.
We know how these little stories help the children remember. After 35+ years of teaching, I have lots of little stories and "tricks up my sleeve". Recent brain research shows us these little stories help make the connections in the brain so the children can build their knowledge. Plus, it's fun!
One of my favorite games has this Band-Aid/ Lasso theme. Click the image for the link!