Here is a fun and simple Halloween activity that is also benign (meaning, it is not scary in the least. Another bonus, for those of you who don't like Halloween, it is a seasonal activity that is about candy, not Halloween).
Kaitlyn did this in her preschool class this year. You can see it is rather simple-- white triangle and tissue paper squares. The tissue paper was not glued (hence the missing square), but rather was dipped in water and put on the paper wet. When it dried, it stuck.
Here is the cool possible bonus. Kaitlyn's teacher has done this in the past, but the tissue paper bled onto the paper, so the color transferred. That is what she was going for (she didn't know what happened--apparently the tissue paper brand or type might be of importance). If yours does bleed, you would want to remove the tissue paper before it dried so it didn't stick to the white paper.
I am going to try this out with different tissue papers and see if I can figure out which papers work for bleeding. My guess is the waxy feeling paper will not bleed while the rougher feeling paper will. I am starting with cheap dollar store paper...I will keep you updated when I have answers, but until then, I wanted you to have the chance to do this if you wanted!