Via this column, we'll explore one grammar rule each week. If you have a grammar question you'd like me to address, please drop me a line at grace.lavigne@prnewswire.com and I'll do my best to answer it.

It's September! And for many, that means the dreaded or eagerly anticipated first day of school. DUN DUN DUN! While Mom and Dad shed tears of joy, kids shed tears of sorrow as they shuffle onto the school bus all did up in new shoes and a fresh outfit. School has its pluses and its minuses.

Whether you're the one going back to school, or maybe just the one pushing kids out the door, make sure you and yours are fully prepared to show off some superior grammar skills by understanding this week's simple but commonly confused lesson:  

Main Rule: It's means "it is" or "it has." Its indicates possession.

If you're not sure, try replacing its or it's with "it is" or "it has." If it sounds OK, use an apostrophe. Examples:

• The school has its recess at noon -- can't wait!
• The school has it is recess at noon (wrong, no apostrophe)
• It's the first day of school.
• It is the first day of school. (right, use apostrophe)

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image via Flickr user kevin dooley