Maybe it's just that time of year but "rigor" to me reminds me of rigor mortis! :) Not talking about that kind of rigor! We're talking about stepping up those Halloween activities so they really make the kiddos think. Some ideas:
1) New uses for pumpkins-what can we use pumpkins for other than making pies and decorations?
2) Remake a holiday classic-The Grinch Who Stole Halloween? A Halloween Carol? What details would change if the holiday changes?
3) How would a Halloween celebration change if it took place in another season?
4) Invent the perfect candy to receive when trick-or-treating.
5) Invent a new Halloween tradition.
6) Design the perfect trick-or-treating route.
7) Is it right or wrong to turn pumpkins into jack-'o-lanterns?
8) Adapt a scarecrow for different settings-the North Pole, the desert.
9) Pretend there is a candy shortage-what can people give away instead? How will that change the typical Halloween traditions?
10) How has Halloween/popular costumes changed over the years-past, present, what will it be like in the future?