This unit describes four secondary school activities related to the geography of the Great Lakes. In Activity A students develop map skills as they study the lakes' positions and associated cities; these skills are applied to the St. Lawrence Seaway in Activity B. Activities C and D involve learners in solving perimeter, area, distance, rate, time, and volume problems using the Great Lakes area for examples. The teacher's guide includes a materials list, overview of the unit, objectives, teaching suggestions, evaluation items, and an answer key. The student workbook is also provided. (Author/WB)