You are such a good paretn to volunteer. Well done!

Maybe the kids could paint paper plates orange and then draw scary faces (like they do for Jack-o-lanterns) with black marker or crayon. Then use a bit of green brenex or construction paper for the stem.

I have done your spider idea with my kindy class and they look great.

Black Cats- out of paper plates (1 small 1 large painted black) and then stick some eyes and pointy ears and a tail.

If you google halloween craft ideas for pre schoolers you should get a heap of ideas.

Good luck and have fun!