This activity is more about diffusion and the characteristics of some kids of materials than it is about bats, so you can get creative with what your balloon or glove represents. I used colorful balloons and pretended I was helping Willy Wonka smell test his latest Everlasting Gobstopper flavors. You can Turn yours into smelly ghosts, jelly fish, moose, whatever you want. The directions are clear and I love that an explanation for why this works is included. I'd say the only tricky part would be trying to add the smells without the kids seeing what you did cause part of the fun is the guessing. I imagine you could use essential oils too, though be careful, some can be very strong and some people may have allergic reactions. I would also recommend making sure that the smell factor be delivered well within the vessel so that when you go to tie the end, it doesn't get all over your fingers.