10. How can the effects be controlled?

diagram in form of a triangle made up of 4 smaller triangles to outline factors used to control reactions

“How can the effects be controlled”? Is a question that involves making choices about which internal and external parameters to modify to maximize benefits and minimize costs and risks. While outcomes can be predicted based on models, in real processes there are often many variables which cannot be easily controlled, and many conditions that constrain the processes. Feedback loops of testing and refining are often used, resulting in design processes that converge on a desired outcome (maximizing, minimizing, or stabilizing output), usually making tradeoffs among different properties (such as price, quality, safety, and environmental impact). This chemical thinking question is often central to design activities, such as producing biomass or reducing the toxicity of combustion exhaust fumes.

The Reducing Phosphorus formative assessment was developed by a past ACCT cohort member.


The Reducing Phosphorus formative assessment targets the benefits, costs, and risks of transforming matter. The chemical of interest in this task is phosphorus, which causes algal blooms when the concentrations in waterways are too high.