This unit, which looks at applications of linear algebra to population studies, is designed to help pupils: (1) understand an application of matrix algebra to the study of populations; (2) see how knowledge of eigen values and eigen vectors is useful in studying powers of matrices; and (3) be briefly exposed to some difficult but interesting theorems of linear algebra, such as the Perron-Frobenius Theorem. The material examines mathematical models that are aids in analysis and prediction. The unit includes exercises, with answers to these problems provided near the conclusion of the document. The module contains two appendices. The first provides a program written in BASIC which computes powers of a matrix. A sample run is also shown. The second appendix goes into further examination of the powers of a Leslie matrix. (MP)