Incorporating career-specific vocabulary and contexts, each unit offers stepby-step instruction that immerses students in the four key language components: reading, listening, speaking and writing. Career Paths: Environmental Engineering addresses topics including aspects of environmental engineering such as ecosystems, irrigation, water treatment, air pollutants and career options.The series is organized into three levels of difficulty and offers a minimum of 400 vocabulary terms and phrases. Every unit includes a test of reading comprehension, vocabulary and listening skills and leads students through written and oral production.