The Freshwater baMEL

The Freshwater baMEL asks students to weigh the connections between evidence and alternative explanations about the quantity and quality of freshwater resources. The availability of usable freshwater as the world's population grows is a critical environmental issue facing Earth and its inhabitants.

Below are links to resources that will help students use the Freshwater baMEL and develop an understanding of the spatial complexity of access to freshwater resources.


This article provides an introduction to the Freshwater build-a-MEL (baMEL). It is useful even if you are using the Freshwater pcMEL with your students. The primary difference between the pcMEL and the baMEL is that with the pcMEL students are given two models and four lines of evidence in a preconstructed diagram where as with the baMEL students choose two models from three and select four lines of evidence from eight to create their own MEL diagram.

Freshwater Resources Article Cover
Freshwater Resources: The Challenges of Quantity and Quality (Acrobat (PDF) 529kB Feb8 21)

Next Generation Science Standards Performance Expectations

MS-ESS2-4: Earth's Systems

  • Develop a model to describe the cycling of water through Earth's systems driven by energy from the sun and the force of gravity.

MS-ESS3-1: Earth and Human Activity

  • Construct a scientific explanation based on evidence for how the uneven distributions of Earth's mineral, energy, and groundwater resources are the result of past and current geoscience processes.

MS-ESS3-3: Earth and Human Activity

  • Apply scientific principles to design a method for monitoring and minimizing a human impact on the environment.

HS-ESS3-2: Earth's Systems

  • Analyze geoscience data to make the claim that one change to Earth's surface can create feedbacks that cause changes to other Earth systems.

HS-ESS3-1: Earth and Human Activity

  • Construct an explanation based on evidence for how the availability of natural resources, occurrence of natural hazards, and changes in climate have influenced human activity.

The Models

Model A: Earth's freshwater is abundant and will remain so even in the face of global climate change.
Model B: Earth's freshwater challenges will be solved by engineering solutions.
Model C: Earth has a shortage of freshwater, which will worsen as our world's population increases.

Student Handouts

Lines of Evidence

Evidence #1: Land use changes have generated large pressures on freshwater resources. These changes are affecting both water quality and availability.
Evidence #2: The world's population is increasing. This stresses the supply of freshwater.
Evidence #3: Groundwater provides freshwater to many people around the world. In many places, people are using groundwater faster than it is replaced by precipitation.
Evidence #4: Water reclamation and desalination are expensive. The costs vary depending on location.
Evidence #5: Advances in engineering have led to better access to quality drinking water. At the same time life expectancy and quality of life have improved.
Evidence #6: Glaciers are a source of freshwater in many parts of the world. Glacial ice mass is decreasing worldwide.
Evidence #7: Microclimates are climates of very small areas that usually differ from the surrounding areas. Scientists are developing high-resolution models to accurately predict microclimate trends in freshwater availability.
Evidence #8: In the contiguous US, average temperatures and precipitation have increased since 1901. From 2000-2015, the US was abnormally dry with some parts of the country in moderate to severe drought.

Student Handouts

Other Resources

This Plausibility Ranking Task (PRT), which may be completed prior to using any MELs, helps students to understand the role of evidence in supporting or refuting models.

Virtual baMEL

*NOTE: The virtual materials below are from an older version of the activity than what is posted above.

The Google Drive folder below contains MEL resource documents in the Google formats. In order to maximize the flexibility of our activities, the MEL Project Team wanted to make more resources compatible with virtual settings. We have made our MEL scaffolds available in Google formats, so that they can be copied, modified, and uploaded more easily on a variety of platforms and devices. Please note that to access all the materials for each MEL scaffold, you will need a Google account. View the README file first.

Digital Resources

Passage of Water
Passage of Water is a three-part interactive experience created in collaboration with artist, Yiyun Kang, NASA and Google. Learn about freshwater availability and engage with possible solutions to avoid a water crisis.

Freshwater Education Resources NOAA
Freshwater Education Resources from NOAA contains lessons and activities related to the water cycle, watersheds, flooding, and pollution plus the Great Lakes ecosystem, which is the largest supply of freshwater in the world.

Climate Change Impacts on Freshwater Resources EPA
EPA's Climate Change Impacts on Freshwater Resources describes three key impacts from climate change, the role of freshwater in the U.S. economy and the inequitable distribution of freshwater resources, particularlly with regard to indigenous and low-income communities.

Water Science School USGS
Water Science School from the USGS offers information on many aspects of water, along with pictures, data, maps, and teaching resources for water education. It includes a unique global water cycle diagram that includes how human water use affects where water is stored, how it moves, and how clean it is.

Will There be Enough Freshwater CC Module
Will there be enough fresh water? is a module from The Concord Consortium's High Adventure Science series. Explore the distribution and uses of fresh water on Earth. Use models of porosity and permeability, run experiments with computational models, and hear from a hydrologist working on the same question.