Evelyn Krauss, a second-grader at Delaware’s Carlisle Elementary School, explains her invention, “ecoRings,” to judges Aaron Cook and Joe Uher at Delaware City Schools’ “Invention Convention” Friday morning at the district’s Technology Center. Students were tasked with finding a problem and then inventing an item that solves the problem. Krauss told the judges that her “ecoRings” are similar to other plastics used to hold six-packs of soda but Krauss said her rings are biodegradable and break away when animals are caught in them. Cook and Uher and curriculum directors for the district volunteered to judge the inventions.