Put real spiderwebs on paper. preserve a spiderweb on paper to explore/look at. or put the black paper behind it so it can be seen in detail and then take a picture so you don't have to destroy the spider's web.
Richard Shilling on Land Art for Kids what a great idea for outside leaf/nature sculptures. make sure to watch an andy goldsworthy documentary too! Should you appreciate arts and crafts you really will really like this site!