Coat or no coat?

Fall made me smile with its cool weather, indigo skies, and amazing colors.  Today was little different save for the significantly cooler temps.  It was time to pull out the warmer coats and squeeze bundled kids into car seats.  

Now my 11yo thought he would hold on to summer longer and dressed in a t-shirt and shorts, leaving the coat conveniently on the hook.  

So, here is a mommy question for you.  To what extent do I fight with my tween?  Is the coat that big of a deal?  Am I frustrated simply because I don't want others to look at ME like I am crazy for sending my child to school ill prepared for the chilly weather?

Believe me, there are many things to fight for.  I will always fight for my kids, but too often I find myself fighting with my kids.  

What are some ways that you choose your battles?