Stability and Change
"Understanding the feedback mechanisms that regulate the system’s stability or that drive its instability provides insight into how the system may operate under various conditions.”
Source: NRC Framework
Introduction to Stability and Change
Source: NGSS Appendix G
Stability and Change are the primary concerns of many, if not most, scientific and engineering endeavors. “Stability denotes a condition in which some aspects of a system are unchanging, at least at the scale of observation. Stability means that a small disturbance will fade away—that is, the system will stay in, or return to, the stable condition. Such stability can take different forms, with the simplest being a static equilibrium, such as a ladder leaning on a wall. By contrast, a system with steady inflows and outflows (i.e., constant conditions) is said to be in dynamic equilibrium. For example, a dam may be at a constant level with steady quantities of water coming in and out.... A repeating pattern of cyclic change—such as the moon orbiting Earth—can also be seen as a stable situation, even though it is clearly not static.
“An understanding of dynamic equilibrium is crucial to understanding the major issues in any complex system—for example, population dynamics in an ecosystem or the relationship between the level of atmospheric carbon dioxide and Earth’s average temperature. Dynamic equilibrium is an equally important concept for understanding the physical forces in matter. Stable matter is a system of atoms in dynamic equilibrium.
“In designing systems for stable operation, the mechanisms of external controls and internal ‘feedback’ loops are important design elements; feedback is important to understanding natural systems as well. A feedback loop is any mechanism in which a condition triggers some action that causes a change in that same condition, such as the temperature of a room triggering the thermostatic control that turns the room’s heater on or off.
“A system can be stable on a small time scale, but on a larger time scale it may be seen to be changing. For example, when looking at a living organism over the course of an hour or a day, it may maintain stability; over longer periods, the organism grows, ages, and eventually dies. For the development of larger systems, such as the variety of living species inhabiting Earth or the formation of a galaxy, the relevant time scales may be very long indeed; such processes occur over millions or even billions of years”.
K-12 Progressions for Stability and Change
Source: NGSS Appendix G
Critical Questions
Source: Peter A'Hearn/ CrossCut Symbols
What causes change in this system?
What causes stability in this system?
Are there feedbacks that make this system more or less stable?
Engineering- How can we make the system more stable? How can we make it change?
What is the time scale for this system to remain stable or change?
If the system is stable, what would cause it to change?
If the system is changing, what would make it become stable?
Is the stability static or dynamic?
How does stability and change in this system compare with other systems I have learned about?
What other crosscutting concepts relate to stability and change in this system?
Based on what I've learned, what other symbol could be used to represent Stability and Change?
Questions connecting to Practices
Source: Peter A'Hearn/ CrossCut Symbols
Asking Questions- What causes change in this system? What causes stability in this system?
Defining Problems- How can we make this system more stable? How can we make it change?
Models- How can we model how this system changes?
Investigations- Can we design an investigation to study what leads to stability and change in this system?
Data- What does the data tell us about what affects the stability of this system?
Using Math- How can we use math to measure the rate of change in this system? Can math describe the balance that keeps it stable?
Computational Thinking- How can computers be used to analyze stability and change in this system?
Explanations- How can I explain why this system changes or remains stable?
Solutions- Have me made the system more stable? Does the system respond to change the way we want it to?
Argument- What is the evidence for the stability and change in this system?
Information- What is already known about stability and change in this system? How can I best communicate what I've learned about stability and change in this system?
Prompts for Stability and Change
This set of prompts is intended to help teachers elicit student understanding of crosscutting concepts in the context of investigating phenomena or solving problems. Source: STEM Teaching Tools
Learn more about Stability and Change
Bozeman Science Video - Concept 7 - Stability and Change
Wonder of Science Graphic Organizer: Stability and Change - Google Draw or PDF
Webinar: Stability and Change