My Husband Wonders if We Can Play with Porcupines in Heaven

First of all, I was not the one who corrected this sign -- or most of the others I saw in many bathrooms in Denali National Park in Alaska.  I would view that as defacing property, which I have strong convictions against.  But, it did show me that I am not the only one who notices these things.  Perhaps the National Park Service should hire a grammarian?  Or would that be a punctuarian?  

For the correction, as it is written, it is only for one animal's safety.  If it were meant for all of the animals, it should be written "Animals' Safety", though I'm not sure why they threw in all those capital letters. 

My students can say the rule:

If there is not an "s", add apostrophe "s".

If there is an "s", just add an apostrophe.

Example:

1 cat               the cat's dish               2 cats          the cats' dishes 

1 mouse         the mouse's cheese     2 mice         the mice's cheese

To read about more of these, click here.