Exploring Crosscutting Concepts: Scale, Proportion and Quantity

Why is it so hard to predict the weather? 

A major obstacle in forecasting the weather and accurately predicting the rate of climate change is the challenge of building system models and simulations that are able to account for EVERYTHING: from the very small to the very large.  In order to predict what clouds will form where, and what it is exactly they will do, would require a computer simulation that could account for the movement of all every molecule of water through the entirety of the Earth's atmosphere as well as countless other particles also found in the atmosphere, the oceans, and on the land.

This challenge of accounting for phenomena at multiple scales, or the dynamic range problem, grounds Kevin Heng's argument in his recent article The Nature of Scientific Proof in the Age of Simulations from the May 2014 issue of American Scientist.  

For Professional Development

This article provides a great visual to to anchor discussions of the crosscutting concepts of scale, proportion, and quantity.  Chunks of the text are also useful for engaging teachers in thinking about what counts as evidence in the community of astrophysicists and how the limits of our understanding the physical world impact what we can say about it at any moment.  

I have partnered this article with the curriculum from the Inquiry Project where teachers are constructing a 2 bottle system to develop explanations based on evidence about how water from one heated bottle ended up inside another bottle which is attached to it. This PD curriculum provides various intriguing phenomena for teachers to explore so that they can begin to develop a mental model to make sense of how water could travel through air and why it would.

Elementary teachers setting up their two-bottle system summer 2014

Specific to student learning about the NGSS Crosscutting concepts of scale, proportion, and quantity: "In considering phenomena, it is critical to recognize what is relevant at different measures of size, time, and energy and to recognize how changes in scale, proportion, or quantity affect a system’s structure or performance." (Appendix G NGSS).

Our weather and climate predictions are based upon our understanding of these three elements and their interaction in either physical closed systems that we construct or computer simulations that we run. In order for teachers to begin to explicitly discuss the impact of these three measures, they need to engage in multiple experiences and discussions about different systems. Beginning with a system that builds teachers' conceptual understanding of the movement of water, is a place to start where we can complicate the often memorized "water cycle" and begin the work of teacher learning about the most important component of our modern planet.