The senior school Mathematics syllabus is often restricted to the study of single variable differential equations of the first order. Unfortunately most real life examples do not follow such types of relations. In addition, very few differential equations in real life have exact solutions that can be expressed in finite terms. Even if the solution can be found exactly it may be far too difficult to be clearly articulated such as those that form an infinite series. In either case, these "real life problems" are well beyond the scope of the secondary student to solve. Does this mean that many of the exciting relationships and models found in the real world cannot be studied by the secondary student? What if the behaviour of the solution was just as important as the solution itself? What device can be so powerful? Enter the "phase plane"--a geometrical device. To understand how the phase plane works, the author first considers the "predator-prey model" defined by Alfred Lotka in 1920 and Vito Volterra in 1926 called the Lotka-Volterra System. Although many mathematical models exist whose solutions are quite complex, this need not prevent students from exploring such ideas. The phase plane method gives the student another tool in their ever expanding "tool box" to explore an exciting area of mathematics. (Contains 3 figures.)