Starting with animal dung/horse manure discuss the animals and plants that are connected to these animals, then build a food web.
Science content (2016 curriculum):
Biology: Food Webs, Ecosystems, Biomes (3, 4)
Curriculum connection (2005 science topic):
Life Science: Needs of Living Things (grade 1)
Life Science: Animal Growth and Changes (grade 2)
Life Science: Habitats and Communities (grade 4)
Life Science: Ecosystems (grade 7)