Unit 3 – Symbols and ClassesBy Admin / December 29, 2014 You must first complete Unit 2 – Product Labels before viewing this LessonPlease sign up for the course before starting the lesson. In this unit participants will learn about the 8 symbols and classes used to identify specific hazards. Unit 2 - Product Labels Unit 4 - Material Safety Data Sheets Back to: Workplace Hazardous Material Information System (WHMIS)