Halloween lends itself to lots of strange science activities, from spooky dry ice experiments, to cosmic black light effects and strange magical potions that disappear and reappear, that change colour unexpectedly or become slimy and ooze.
You can make your own shrunken heads from carved and dried apples (it will be as if those apple dolls your grandparents made became apple zombies).
It's also a time to look at some truly bizarre creatures , even more bizarre creatures and maybe do a little owl pellet detective work. If you have access to a microscope, you can see a whole world of alien-looking creatures--from pond critters & close-up insects to bacteria (in fact, you may want to try and culture some bacteria of your own--see below). Strange & spooky science effects can also be found in the kitchen with possessed dancing raisins & living sludge bread (yeast & sourdough).
To culture bacteria, you will need a petri dish (or clean, clear container), some powdered agar (you can find this at health food stores and science suppliers), chicken broth (to use as a nutrient base), cotton swabs, and a place to store the samples. Boil the chicken broth then add the agar and stir well. Pour the mixture into petri dishes, cover and refrigerate to set.
Use the cotton swabs to collect samples from anywhere you suspect germs & bacteria may be found. Try doorknobs, computer keyboards, pet mouths, human mouths--and so on. Gently brush each swab along the top of a gel, label and seal the dish. Repeat for each sample. Store the samples at room temperature, or experiment with making several copies and storing at various temperatures for several days or even weeks. Examine your results under a microscope if possible.
Of course, if you are doing this as a controlled experiment, you will need to be much more careful about preparing and storing the cultures in order to avoid contamination, but for pure exploration, these instructions should suffice.
Other ways to culture bacteria can be edible, such as making your own yogurt or cheese. In fact, when you eat yogurt, you are actually eating live bacterial cultures--poor things! They're being EATEN ALIVE!!!
More weird science can be found here.