http://www.littlegiraffes.com/spiders.html
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Paint palm and four fingers of child's hand with black paint. Put hand down on paper with fingers spread to make 4 spider legs. Paint again. Turn paper around and put palm over same area, but fingers facing the opposite direction. This looks nice as a block on a Halloween quilt.
Spider Web
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Cut about 16 slits around the edges of a brightly colored paper plate (orange, lime green). Tape a long piece of black yarn to the back of the plate. Then weave the yarn back and forth across the plate's front to form a web. Tape down in back and accent the web with a spider ring.