Pumpkin Math
We first read How many Seeds in a Pumpkin? Be warned, pre-read the book. The end of the book gives away a little too much information to make determining your own seeds an actual guess.
Then, we break open the math with this activity I found on Teachers Pay Teachers. I wish I had thought of it, but all credit has to go to All4Math. My students thoroughly enjoyed working through the packet this year. We took her ideas and created a large chart of our data.
This will easily take up most of your day - if not all of it. I had to start it a day early last year so we could finish and even then it was tight. The kids love it because it involves pumpkins, but since you're not actually carving jack-o-lanterns, most families will be fine with the seasonal activity.
Movie Time
After lunch, as the students are starting to get trick-or-treating on their brains, I break out whatever treats we have (I usually make cupcakes and put 3 Bertie Botts Every Flavor Beans on top - those are fun to watch!) and The Wizard of Oz. Strange as it seems, many students have never seen this movie. I guess it's because it's considered old compared to all the newer movies out there.