I live in Iowa, the Jell-O Capital of the world. Iowa does or did consume more Jell-O per capita than any place else in the world. Knox Blocks were a very popular snack food early in my teaching career. Knox Blocks are made by adding extra gelatin to Jell-O which stiffens it up and keeps it solid but seductively wiggly at room temperature, the Jell-O is then cut up into squares called Knox Blocks(after the seller of the extra gelatin that was added). I discovered through observation of numerous specimens that Knox Blocks might also be used by crime scene investigators as an excellent transfer agent for finger prints.
Forget the Iowa Test of Basic Skills, the proof of a true blue elementary teacher is one who can accept a proudly presented, fingerprint covered Knox Block on a piece of crinkled wax paper from an elementary student with stringy dirty hair and a yellowed see-through hand me down T-shirt and eat it with a smile, a thanks, and a deep trust in their own digestive system’s ability to kill whatever might be living on its surface.
I did discover that the Knox Block craze could be somewhat slowed in upper elementary students by assigning a research paper on how gelatin was made.