The Oklahoma Plumbing and Natural Gas Exam Prep topics include Isometrics, Calculations, Plumbing, Cutting and Notching, Gas Pipe Sizing and Safety. The course includes narrated highlighting guides, practice tests, theory, calculations, instructor support and test-taking tips and strategies.@HomePrep is a National Leader in online education. With over 100,000 satisfied students and a course catalog of over 1,000 classes, we are here to help you – Invest in Yourself. The highlighting guides and quizzes are designed to familiarize students with testing materials. We do not provide students with exact test questions, as the state does not release this information.