For many chemistry and physics students, some of the most frustrating problems involve dimensional analysis. This is a very important concept that is more related to mathematics and equation consistency than the sciences. A dimensional analysis tutorial is offered at the physics department's Web site of the University of Guelph. It is an excellent guide that helps students understand the five dimensions of physical quantities and how to work with units to achieve correct results. There are seven quizzes and a final post-test that assess the student's grasp of the topic, with answers given after each exercise for comparison.