Teaching unit that culminates in a field trip. Students explore the needs of salmon at each stage of their life cycle and then go on a field trip to investigate a local aquatic habitat and its potential as a salmon habitat. They observe the physical characteristics of the stream and argue from evidence whether or not salmon could survive well there. Extensions are included to gather additional evidence by measuring the water quality parameters of water temperatures, dissolved oxygen, and pH; measuring stream velocity, collecting and identifying macroinvertebrates as indicators of water quality, and observing human impacts.