Filled with high interest exercises, this Grade 4 Unit 4workbook focuses on work and energy, simple machines, complex machines. Lifepac science curriculum brings the physical world of God's creation into focus. Students conduct experiments to reinforce scientific concepts, such as machines. Perfect for students who flourish in a self-paced, individualized learning format, each consumable Lifepac combines lessons, exercises, projects, reviews, and tests. Paperback.