SimRiver Simulation - Diatom Project

Mayama, S., Tokyo Gakugei University
Type Category
Instructional Materials
This resource, vetted by NSTA curators, is provided to teachers along with suggested modifications to make it more in line with the vision of the NGSS. While not considered to be “fully aligned,” the resources and expert recommendations provide teachers with concrete examples and expert guidance using the EQuIP rubric to adapted existing resources. Read more here.



The SimRiver Simulation, developed by Dr. Shigeki Mayama’s lab at Tokyo Gakugei University, models human impact on water quality of a river. Settings within the simulation help students to make sense of this phenomenon by allowing them to mimic changes in land use along the river, population size, the presence/absence of sewage treatment, and season of the year. Using diatoms as indicator species of water quality, students identify diatoms from water samples, determine the saprobic index (a measure of water quality), and compare the impact of different human land and water uses along the river. As students become familiar with the simulation, they can use it to plan investigations and explore possible solutions to mitigate adverse impacts of human actions on water quality, and thus biodiversity. Instructional supports include background information, instructions for using the simulation, a printable student worksheet, and three levels of student support through different challenge settings.

Intended Audience

Educator and learner
Educational Level
  • High School
Access Restrictions

Free access - The right to view and/or download material without financial, registration, or excessive advertising barriers.

Performance Expectations

HS-LS4-6 Create or revise a simulation to test a solution to mitigate adverse impacts of human activity on biodiversity.

Clarification Statement: Emphasis is on designing solutions for a proposed problem related to threatened or endangered species, or to genetic variation of organisms for multiple species.

Assessment Boundary: none

This resource was not designed to build towards this performance expectation, but can be used to build towards it using the suggestions provided below.

Comments about Including the Performance Expectation
Students engage in three-dimensional learning by manipulating values to explore impacts of human activity along a river on the resulting biodiversity of diatom populations - indicators of water quality. When the simulation is run, water samples taken at different locations along the river provide slides of diatoms. Using the provided Diatom Guide, which gives positive reinforcement to students for accuracy and completion of the identification task, students calculate a saprobic index for each water sample. The saprobic index, explained in the simulation, is a measure of water quality based on the number and type of diatom species present in the water sample. Teachers may want to allow students to first use Level 1 and to familiarize themselves with the instructions, the simulation, identification of the diatoms, the calculations, and the provided graphs and worksheets. Once students are comfortable with using the simulation, one suggestion is for students to consider ways to use the simulation to show how to improve water quality when people live on and farm the land along the river. By selecting higher levels, more options are available to the students for their designs.

Science and Engineering Practices

This resource was not designed to build towards this science and engineering practice, but can be used to build towards it using the suggestions provided below.

Comments about Including the Science and Engineering Practice
The best way to access the SimRiver simulation is to click on the SimRiver logo on the home page (lower right side) of the Diatom Project website ( Students should view all parts of the SimRiver simulation in the full screen mode. At Levels 1 and 2, the human usage settings are preset, allowing students to focus on identifying the diatoms and collecting data. At Level 3, students can select all the different parameters including settings for the type of land use (forest, farm, or residential), the population size (from 0 to 10,000), the presence/absence of sewage treatment in residential areas, and season of the year. When identifying diatoms, it is best for students to stay on the simulated microscope slide prior to going to the species table. As students identify the diatoms, a circle appears on the diatom; this circle changes color when it is correctly identified. In this way, students can track which diatoms they have identified. The identification process is expedited by selecting all similar diatoms first (clicking on each one so a circle shows on it) and then selecting the matching diatom in the Diatom Guide. A congratulatory pop-up window tells students when they have correctly identified all the diatom species. At this point, students should go to the species table, where all the species and counts are tallied and the rest of the calculations are either done by the simulation, or calculated by the students, depending on which choice is selected. The simulation supports mathematical thinking by helping students to link the value they calculate to water quality. Teachers may want to reinforce the concept that the diatoms are an indicator species representing an ecosystem. Talking about the role of diatoms in the ecosystem and the consequences of changes in their biodiversity and in water quality will help students to make sense of the impact of human activity on the river as a system.

Disciplinary Core Ideas

This resource was not designed to build towards this disciplinary core idea, but can be used to build towards it using the suggestions provided below.

Comments about Including the Disciplinary Core Idea
Teachers will want to encourage students to think about how human activity ultimately impacts the sustainability of the river ecosystem. It may be helpful to provide students with background information on the role of diatoms in ecosystems - both in providing oxygen, and in providing a critical food supply within freshwater and marine ecosystems. (Natural History Museum of London has an excellent website about diatoms: Students may want to think about what happens when people build farms, homes, and cities that changes the water quality of the river. Did they notice any change in diatom biodiversity or water quality if sewage treatment is used? The SimRiver simulation offers graphs showing the ratio of diatoms in three categories of tolerance to pollution. These graphs can be used as evidence to support explanations in class discussions.

This resource was not designed to build towards this disciplinary core idea, but can be used to build towards it using the suggestions provided below.

Comments about Including the Disciplinary Core Idea
The most obvious feature of the SimRiver simulation is the change in diatom species as a result of different levels of human impact. Some diatom species may thrive in polluted waters, while others disappear completely. Teachers may want to encourage students to compare the biodiversity of diatom species along the length of the river between two extremes of human impact (e.g., forests with no humans to cities with no sewage treatment). Engage students in discussions about how these extremes impact the biodiversity of the river. Teachers may want to prompt students to consider how fluctuations or changes in diatom biodiversity affect the other organisms that live there.

Crosscutting Concepts

This resource was not designed to build towards this crosscutting concept, but can be used to build towards it using the suggestions provided below.

Comments about Including the Crosscutting Concept
The SimRiver simulation allows students to select settings that represent human activities and produce direct evidence of the impact of these activities on water quality. By making comparisons across diverse conditions, students can make claims about specific causes and effects. For example, by selecting only uninhabited forests along the length of the river, students can see what happens under natural conditions. This can serve as baseline data for comparison to human-induced changes in water quality, and consequently, the diatom species.

Resource Quality

  • Alignment to the Dimensions of the NGSS: The SimRiver simulation supports three-dimensional learning as students make sense of how human activity impacts water quality and thus the biodiversity of diatoms within a river. The three different levels of student support offered within the simulation help students to develop and use this tool. The various settings help students to determine cause and effect relationships between human activity and the impact within the river ecosystem.

  • Instructional Supports: This simulation engages students in an authentic scenario of human development along a river that helps them to understand the real-life phenomenon of human impact on biodiversity and ecosystem functioning. The simulation provides wide opportunities for student choices to represent and test their ideas. A worksheet is provided that shows evidence of students’ work and provides a basis for discussion of students’ ideas and explanations of the phenomenon. The simulation uses scientifically accurate representations of diatoms and has been used and evaluated internationally by diatom and ecosystem scientists. It provides differentiated instruction opportunities through the three levels of support, as well as offering support in completing calculations, if this is a barrier for students. Extensions are provided for students with high interest. For example, students may select a button within the simulation that connects with a second simulation that shows underwater views for different levels of water quality. Within this second simulation, students can click on certain areas to learn about other species that tolerate different levels of water quality. The Diatom Project site that contains SimRiver also provides videos with background information about diatoms, videos on how to make slides of diatoms, and links to other diatom guides. Please see the NGSS@NSTA Hub for another curated resource that incorporates and extends this resource, “The Microscopic World of Diatoms.”

  • Monitoring Student Progress: SimRiver provides many opportunities to monitor students’ progress as they develop and use the simulation and make sense of the connection between human activities, water quality, and diatom biodiversity within the river. However, there are no assessments or rubrics provided. The student supports provided help this simulation to be accessible for all students.

  • Quality of Technological Interactivity: The simulation is easy to use and works well. As stated earlier, it is important to use the full screen so all parts and functions can be seen. The many available options allow different students have different experiences with the simulation.