This free PD on Saturday, September 21, 9-12 a.m. will include the hands-on activity, Enzymes Help Us Digest Food, the analysis and discussion activity, Introduction to the Functions of Proteins and DNA, and a talk on Protein Structure and Function in Archaea. The registration deadline for Philadelphia teachers to be guaranteed supplies is September 4; the final registration deadline is September 18.  Additional information about the location on the University of Pennsylvania campus and a link to register for this PD are available at https://sites.google.com/site/biologypd/home/professional-development.