Discussion among the groups measuring this experiment under a variety of conditions should lead to a better understanding of mechanism. This experiment is best completed before or during a discussion of kinetics. It can take from two-three weeks, depending on the nature and number of variations chosen by the instructor and the students. Teams of three persons are best suited to keep order and maintain good technique and data. A week allowed for calculations and discussion is also helpful.
Soil analysis is often a mystery to the general public.
Students will learn to prepare standards in ppm mode, explained in the experiments themselves, and thus have a better grasp of that elusive term which is ever present in articles about the environment and toxic, or even beneficial, materials. Spring is probably the best time for this module in some parts of the country where soil is not so readily sampled during winter months. The module could take from two to three weeks, depending on the time required to prepare standards and the number of samples to be studied.