Look at different animals, discuss the differences and similarities between us and them, then extract the molecule that makes those differences: DNA.
Science content (2016 curriculum):
Biology: Features, Adaptations of Living Things (K, 1, 3, 7)
Biology: Evolution, Natural Selection (7)
Curriculum connection (2005 science topic):
Life Science: Animal Growth and Changes (grade 2)
Life Science: Diversity of Life (grade 6)
Physical Science: Chemistry (grade 7)