The Chemistry Tutor: Learning by Example DVD Series provides an introduction to chemistry through step-by-step example problems. Emphasis is placed on giving students confidence in their skills by gradual repetition so that the skills learned are committed to long term memory. This episode covers ionic compounds with polyatomic ions, including the concept of a polyatomic ion as simply the grouping of atoms that has a net charge associated with it. Grades 9-Adult. 36 minutes on DVD.