In MACOS, the concept was "the chain of life" or a "lifeline": the entire history of a living thing. The course started with a simple lifespan in the form of the Pacific Coast salmon. It then moved on to the more complex life form of the herring gull, introducing concepts such as nurturing. The lifespan of the baboon was next examined, particularly within the societal context afforded by the baboon troop. The differences between innate behaviour and learned behaviour were introduced. Finally, the study opened up into a study of a man's lifespan with a case study of Netsilik Eskimos. This also included the interaction between the Netsilik and other life forms, such as reindeer and seals.
The course comprised a self-contained kit of course materials, film cassettes, visual aids, and games. Some of the activities were very imaginative; a game based upon reindeer migration had a loaded die to introduce discussion about instincts, and a paper seal would be cut up and shared among class members representing various people in the Netsilik community, according to a ritual governing who was entitled to which part of the animal.
The emphasis of the course was upon learning particular skills within the teaching process, not upon the significance of the content. This included the necessity to ask questions, discuss, and reach conclusions based upon evidence and argument.
The course was much criticized in the United States because of its emphasis upon questioning aspects of life, including belief and morality. It was particularly targeted by fundamentalist groups, evidenced by quotations included in the course booklet. In 2004, the National Film Board of Canada produced Through These Eyes, a documentary about the controversey surrounding MACOS, and more generally about the interplay between politics and education.