Seventh graders are working in different groups--disease, potato, sugar, horse, and corn--to investigate how these "seeds of change" altered the course of history. Dr. Jeff Gerber, a pediatric infectious disease specialist at CHOP, spoke about modern epidemics, vaccines, clean water, "superbugs," and the human microbiome. Innovations related to inserting helpful bacteria into a patient's digestive tract were a highlight. Two words to hook any 7th grader: poop transplant. Dr. Eric Cantor, a dentist, spoke to the students who are focusing on sugar as their "seed of change." From cavity formation to Philadelphia's controversial soda tax effort, Eric made it clear that while sugar may be sweet, it also has a bitter side!