The effectiveness of three case studies and associated teamwork to stimulate interest of college freshman in engineering was investigated by observing students. Case studies were assigned as laboratory team exercises in an introduction to engineering course at Auburn University. Student interest in the case studies was evaluated qualitatively based on the use of communication, decision making, and application of basic preparatory knowledge. Evaluations were made of laboratory sections as a whole, for four sections. The greatest student interest and enthusiasm in a case study occurred when there was not an existing "right or correct" answer and the answer was open-ended. Student interest was the least when the best answer to a case study was already known by the students. The order in which case studies are assigned was found to be important to prevent biasing student judgment with previous case studies. Case studies selected for a freshman course should be structured and limited in technical scope so students have more time to make and support decisions. Teamwork and student discussion expanded student perspectives of problems when they were part of a case study solution process. Student discussion of case studies continued beyond completion of the formal assignments when case study outcomes were given at the end of the course. The effectiveness of case studies was found to be very dependent upon the purpose of a case study and the preparation by the instructor to invoke the intangible faculties of curiosity and interest in students. The measures of effectiveness in using case studies as learning tools should be based upon thoroughness of student reasoning, ability of students to communicate their ideas, and the presentation of supporting rational for their decisions.