Leaf Impressions (a model for carbonization) , Kentucky Geological Survey. Uses standard leaf-pressing activity for demonstrating idea of carbonization.
http://utahscience.oremjr.alpine.k12.ut.us/sciber03/elem/sciber4/4th/fossils/HTML/moldyold.htm Moldy Oldies, Utah State Office of Education. Provides short background on different types of fossils and then provides instructions for three activities to illustrate how fossils form. The first models replacement fossils with salt, colored water, and sponges. Film traces uses black paint and a leaf to make a stamp, or impression of the leaf. The third activity involves making casts and molds with different colored clay.
http://www.sdnhm.org/exhibits/hunters/tguide_hunters.pdf Fossil Hunters , Sand Diego Natural History Museum . Scroll to page 9 for activity in which you coat leaves with ink and make impressions on paper to mimic carbonization. Also, povides simple instructions for making impressions in clay with plastic dinosaurs and then filling the footprints with plaster to make the molds.