Thoughts about the Launch For most students, the fact that the light intensity decreases as the depth increases is intuitive. All of their conjectures illustrate this fact. Sample student-generated conjectures on the relationship between light intensity and depth.
Students frequently disagree on the shape of the curve.
These differences are a result of two informal yet incorrect observations. A second belief is that near the surface of the water, there is little change in the light intensity and so the curve must have an initial gradual change. This simple question of how the light intensity changes as a function of depth provides an excellent catalyst and center for the following light activity. The on-line investigation separates the data collection and analysis phases. The on-line investigation also outlines the methods of analysis fairly explicitly.