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Mass Balance Model

Robert MacKay, Science Education Resource Center, Starting Point Collection

In this JAVA-based interactive modeling activity, students are introduced to the concepts of mass balance, flow rates, and equilibrium using a simple water bucket model. Students can vary flow rate into the bucket, initial water level in the bucket, and residence time of water in the bucket. After running the model, the bucket's water level as a function of time is presented graphically and in tabular form.

Activity takes about one class period.

Learn more about Teaching Climate Literacy and Energy Awareness»

ngssSee how this Activity supports the Next Generation Science Standards»
High School: 5 Cross Cutting Concepts, 5 Science and Engineering Practices

Climate Literacy
About Teaching Climate Literacy

Climate system is subject to the same physical laws as the rest of the Universe
About Teaching Principle 5
Other materials addressing 5a
Observations, experiments, and theory are used to construct and refine computer models
About Teaching Principle 5
Other materials addressing 5c
Our understanding of climate
About Teaching Climate Literacy
Other materials addressing Our understanding of climate

Excellence in Environmental Education Guidelines

1. Questioning, Analysis and Interpretation Skills:G) Drawing conclusions and developing explanations
Other materials addressing:
G) Drawing conclusions and developing explanations.
1. Questioning, Analysis and Interpretation Skills:C) Collecting information
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C) Collecting information.
1. Questioning, Analysis and Interpretation Skills:E) Organizing information
Other materials addressing:
E) Organizing information.
1. Questioning, Analysis and Interpretation Skills:F) Working with models and simulations
Other materials addressing:
F) Working with models and simulations.
2. Knowledge of Environmental Processes and Systems:2.1 The Earth as a Physical System:A) Processes that shape the Earth
Other materials addressing:
A) Processes that shape the Earth.
2. Knowledge of Environmental Processes and Systems:2.1 The Earth as a Physical System:B) Changes in matter
Other materials addressing:
B) Changes in matter.

Notes From Our Reviewers The CLEAN collection is hand-picked and rigorously reviewed for scientific accuracy and classroom effectiveness. Read what our review team had to say about this resource below or learn more about how CLEAN reviews teaching materials
Teaching Tips | Science | Pedagogy | Technical Details

Teaching Tips

About the Science

  • This activity introduces students to the science of how mass balance works.
  • Concepts in this activity are essential to understanding climate topics such as how much CO2 is in the atmosphere.
  • The mass balance concept is also applicable to energy concepts like oil reserves or energy loss from a home, which is one of the examples provided.
  • This activity can also be used to introduce very basic concepts of climate modeling.
  • Comments from expert scientist: Good, clear explanation of mass balance, and CFC / CO2 related activities offer good real-life (and up-to-date) examples of its use.

About the Pedagogy

  • This activity is very thorough and contains all the elements needed to present to a college class.
  • The activity contains simple models that run in a browser, plus question sheets, answer key, and follow-on activities.
  • As many students are put off by math, this activity does an effective job of walking them through the concepts in a user-friendly, non-intimidating manner.

Technical Details/Ease of Use

  • All the needed elements are supplied. Student activity is presented in three formats: online, PDF, and Word.

Related URLs These related sites were noted by our reviewers but have not been reviewed by CLEAN

The activity contains a related lesson plan that may be of interest: Using Mass Balance to Understand Atmospheric CFCs

Next Generation Science Standards See how this Activity supports:

High School

Cross Cutting Concepts: 5

Cause and effect, Scale, Proportion and Quantity, Systems and System Models, Energy and Matter, Stability and Change

HS-C2.4:Changes in systems may have various causes that may not have equal effects.

HS-C3.5:Algebraic thinking is used to examine scientific data and predict the effect of a change in one variable on another (e.g., linear growth vs. exponential growth).

HS-C4.3:Models (e.g., physical, mathematical, computer models) can be used to simulate systems and interactions—including energy, matter, and information flows—within and between systems at different scales.

HS-C5.2:Changes of energy and matter in a system can be described in terms of energy and matter flows into, out of, and within that system.

HS-C7.1:Much of science deals with constructing explanations of how things change and how they remain stable.

Science and Engineering Practices: 5

Asking Questions and Defining Problems, Developing and Using Models, Using Mathematics and Computational Thinking, Constructing Explanations and Designing Solutions

HS-P1.2:ask questions that arise from examining models or a theory, to clarify and/or seek additional information and relationships.

HS-P2.3:Develop, revise, and/or use a model based on evidence to illustrate and/or predict the relationships between systems or between components of a system

HS-P5.2:Use mathematical, computational, and/or algorithmic representations of phenomena or design solutions to describe and/or support claims and/or explanations.

HS-P5.5:Apply ratios, rates, percentages, and unit conversions in the context of complicated measurement problems involving quantities with derived or compound units (such as mg/mL, kg/m3, acre-feet, etc.).

HS-P6.2:Construct and revise an explanation based on valid and reliable evidence obtained from a variety of sources (including students’ own investigations, models, theories, simulations, peer review) and the assumption that theories and laws that describe the natural world operate today as they did in the past and will continue to do so in the future.

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