Unit 3 – Symbols and ClassesBy Admin / November 30, 2014 March 21, 2018 You must first complete Unit 1 – Introduction to WHMIS 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 4 - Material Safety Data Sheets Unit 1 - Introduction to WHMIS Back to: Workplace Hazardous Material Information System (WHMIS)