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BayLab: Can We Save the Bay?

Teacher's Guide

Tips for Teachers


Step By Step through the Interactive

Students will follow this sequence as they complete BayLab: Can We Save the Bay?

Students entering the interactive are introduced to the fact that populations of some organisms are decreasing in the Bay—filter feeders (oysters and mussels) and bay grasses (eel grass and wild celery) are dying off. The importance of these organisms to the ecosystem of the Bay is described (filter feeders clean the water and Bay grasses provide food, oxygen, and shelter). The challenge for the student is to figure out if it is possible to reintroduce these organisms to help restore the health of the Bay.

Students are given some information about the Bay ecosystems with an emphasis on the fact that organisms depend on each other and their environment to survive. Changes in salinity, increasing sediment and increasing algae have created imbalances in the Bay ecosystems. Reintroducing organisms such as oysters, mussels, eel grass and wild celery can help restore the Bay. But if they died off once, will they be able to survive now?

In order to answer that question students are sent to the lab to investigate the ranges of conditions tolerated by the organisms. Students then check data from buoys in the Bay to determine if the organisms are likely to survive in any of the areas where the buoys are located.

Because we know the vocabulary of science can be challenging, we have highlighted many words throughout this interactive. By clicking on words in red, students can read a definition of the term.

In the Lab:
When the users enter the lab they see two tanks—one that has wild celery (a bay grass) and fresh water mussels , and another that has eel grass (another bay grass) and oysters. (For more information on these organisms see Eel Grass and Oysters, and Wild Celery and Fresh Water Mussels). These are referred to as "nursery" tanks since the conditions in each tank are ideal for the organisms there. However, the users are told, this is not how it is in the Bay. Can the organisms in the tanks be successfully reintroduced into the Bay given the conditions that exist there now?

When the user clicks NEXT the BayBerry pops up showing the following table:

Table 1

This table fulfills a variety of different functions:

  • The terms "salinity", "turbidity", and "chlorophyll a" are clickable so students can see a brief definition.
  • The units that measure the various tolerances have rollovers to explain them.
  • When the red question mark is clicked an introduction to that factor is shown. This introduction will come up automatically the first time that factor is tested IF the red questions mark for that factor has not been clicked before that time.
  • The "Test It" buttons take users to the virtual lab where they will determine the ranges of that particular factor an organism can tolerate.
  • The table will eventually contain all the data students gather from the virtual experiments they conduct (the data replace the "Test It" button).
  • The buoy icons in the Bay Status column take the user to a map of the Bay where clickable buoys will give current Bay conditions (for more on that see Bay Status: Checking CBIBS Data)

Once at the data table, the student can do a number of things:


THE WATER QUALITY FACTORS (clicking on the ?)

In this investigation students will have the opportunity to determine the ranges of water quality factors in which the test organisms (wild celery, fresh water mussels, eel grass and oysters) can live. The range of salinity (how salty the water is), turbidity (how cloudy the water is), and chlorophyll a (how much algae is in the water) will be determined in the virtual lab.

These three introductions serve to give the students some background information on the water quality factors they are measuring. The introduction to chlorophyll a includes information on dissolved oxygen as well. These introductions are also available as standalone animations on the Videos page and as pages of text on the Scripts page of this Teacher's Guide.

Salinity, in this lab and in the video salinity is measured by a conductivity meter in PSU (practical salinity units) which is equal to parts per thousand.

The salinity gradient in the Chesapeake Bay is introduced in an interactive way—students have to click where they think there will be the saltiest water, and then the least salty water. The fact that organisms can only survive in a certain range of salinity is introduced. For more information about salinity and how to measure it see Salinity.

Turbidity can be measured in a few ways. In this lab and in the video turbidity is measured using a Secchi disk measurement, a measurement often recorded in centimeters. However, a rough conversion is done because the students have to compare their measurements to those of the buoys in the Bay, which are recorded by a nephelometer in NTU (nephelometer turbidity units). This conversion is not obvious to the students—despite the fact that they "use" the secchi disk, the units show up as NTUs.

After defining sediment as loose clay, silt, and sand particles as well as organic matter, the consequences of too much sediment in the water are shown. Because the lighter particles (clay, silt and organic matter) remain suspended in the water they block sunlight. Bay grasses need sunlight and the lack of sunlight can cause them to die. This has a ripple effect through the ecosystem, as organisms that depend on the bay grasses for food and shelter may also die. Too much sediment can also smother bottom dwellers and make it difficult for oysters to attach to reefs. For more information about turbidity and how to measure it see Sediment and Turbidity.

Chlorophyll a concentration is used to determine how much algae is in a water sample. The units used are μg/mL (micrograms/milliliter).

Algae, and their role in the Bay as primary producers, are introduced. Chlorophyll is what allows algae to create food and oxygen by the process of photosynthesis. Too much algae can block the sunlight, overwhelm the filter feeders and release toxins (poisons) into the water. When large amounts of algae die it creates additional problems are created. The algae that aren't eaten die and sink to the bottom of the Bay where they are decomposed by bacteria. This process uses up the dissolved oxygen in the water—sometimes leaving no dissolved oxygen for other organisms. This creates an area with no oxygen called a dead zone.

Nutrients that enter the Bay, such as nitrogen and phosphorus cause algae to grow out of control. These nutrients come from wastewater treatment plants, farms, car exhaust, etc. The algal blooms caused by these nutrients create conditions that are harmful to other organisms. For more information about chlorophyll a and how to measure it, see Algae and Chlorophyll a and the video. For more information about dissolved oxygen see Dissolved Oxygen.



Test it! Buttons

The Test it! button takes the user to the lab to determine the range of a factor the organisms will tolerate. There are three tanks set up in the lab—one control tank and two experimental tanks. Students have to click on the tanks to fill them with water. Initially, the conditions in all the tanks are similar to the "nursery" tank for the organisms chosen to test. Conditions in the control tank remain unchanged throughout the experiment. In any investigation, the control serves as a comparison, in this case a tank where the conditions are known to be favorable. There are two experimental tanks (Tank A and Tank B). Because this is a virtual lab, the conditions in those tanks will be identical, but they serve to remind the students that any good experiment should be repeated to ensure the reliability of the results.

Once the students click on the tanks, they fill with water and are populated with organisms. The clipboards under the tanks display the temperature, and measurements of the three factors being investigated. Initially they are all identical. At the top of the screen is a question—"In what levels of salinity (or turbidity or chlorophyll a) can the organisms survive?" There is also a number line that displays various levels of the factor that can be tested. If the student clicks in the pink (grey/red) zone, they will see a message that lets them know that those values are not realistic. The green zone indicates the measurement in the nursery tank which is healthy for the organisms. (Where there is also a bright red zone displayed it indicates those measurements have been "pre-tested" and the organisms cannot survive at those levels). The grey zone is what the students have to test.

When clicked, this section expands so students can choose a specific level to test.

Once the student chooses the level they want to test it is outlined in red. A dropper or other instrument appears above Tank A. When the instrument is clicked, a Recheck button appears on the clipboard below the tank next to the factor that is being tested. The dropper automatically moves to Tank B and the same thing happens.

Students should click the Recheck button because they have changed that level and need to measure and record the new value.

Instruments Used

When salinity is measured, a conductivity meter slides in, along with a message that reads: "A conductivity meter can be used to measure salinity". That's because salt breaks into charged particles in a solution (such as water). More charged particles in water means there's more salt. See how it works."

When measuring turbidity a Secchi disk descends, along with a message that reads: "A Secchi disk (as in "secky") measures turbidity (or how cloudy the water is). See how it works."

When measuring chlorophyll a fluorometer slides in along with a message that reads "A fluorometer measures chlorophyll a. Chlorophyll a is found in algae. If there's a lot of chlorophyll a in the water, you can assume there are a lot of algae. See how it works."

Clicking on "See how it works" will bring up the BayBerry with a video demonstrating the use of the instrument being used. These videos are also available here.

Conducting the Experiments

Students click on the conductivity meter (or whichever instrument they are using), which takes the measurement in the tank and records it on the clipboard. They repeat the process for Tank B. A button that says "Advance 5 Days" appears. Once the experiment is advanced, the tanks reappear with new clipboards under them. Users then have to rate the condition of the organisms in the tanks as Good, Fair or Poor. They are given a prompt if they choose incorrectly.

Once rated, the students have to repeat the experiment until they find the limit of the range at which the organisms can survive (either the highest level at which organisms can be rated as Fair, or the lowest level at which they are rated as Poor). The slider will record the conditions for the students, favorable conditions indicated by dark green, fair conditions indicated by light green and unfavorable conditions indicated by bright red.

Once students have clicked "Go to PDA" the data table is shown again and the ranges of the factor that are favorable and fair are displayed in the data table. Students can use the BayLab Data Table for Tolerance Ranges to record the data they gather from the virtual experiments.
The ranges that students will find in the experiments can be found here.

Note that for turbidity there are slightly different ranges for Wild Celery and Mussels, and for salinity the ranges are different for Eel Grass and Oysters. Otherwise, the pairs can tolerate the same ranges of conditions.

When testing for chlorophyll a the "Recheck" button appears for both chlorophyll a and for turbidity. This is because the addition of algae will change the turbidity of the water (in addition to changing the level of chlorophyll a). This contributes to the detrimental effects of too much algae and students should be made aware of the connection between the two.

A note about the tolerance ranges:

These ranges were calculated to be as close to reality as possible. An organism's tolerance of a certain factor is determined by any number of variables.

Turbidity ranges were challenging since most students measure turbidity in centimeters with a secchi disk, but the CBIBS buoys measure turbidity with a nephelometer in NTUs. The conversion between these two is rough at best. See Sources and Additional Resources for the conversion and sources.

The range of chlorophyll a tolerated by organisms is the least well defined, in large part because algae levels are determined by so many factors, which also affect the other organisms independent of their effect on algae. This is a good opportunity to discuss the complexity of ecosystems and to differentiate between biotic and abiotic factors in an ecosystem. Although algae are crucial to aquatic ecosystems, chlorophyll a levels can drop to undetectable levels without impacting the health of the ecosystem.


BAY STATUS: CHECKING CBIBS (Chesapeake Bay Interpretive Buoy System) DATA

Students can check the data in the Bay at any time from the data table. Clicking on the buoy icon in the far right corner of the data table, takes them to a map of the Bay with seven buoy icons. A printable version of the map is available here. These are seven of the actual CBIBS buoys that are in the Bay, (see CBIBS for more information). When a buoy is clicked real time measurements from that location in the Bay are displayed for the 3 factors being tested as well as about dissolved oxygen. Students don't test for dissolved oxygen in the lab, but it is crucial to ecosystem health and so is included in the data (see Dissolved Oxygen for more information). The data from that buoy location are displayed in a table alongside any data students have gathered from the virtual experiments:

Table 2

Students can compare the data they have found in the virtual lab to conditions that exist in the Bay and determine if the conditions around specific buoys are suitable for the reintroduction of the organisms. The table clearly shows the data they still need, and they can return to the lab using the Test It! Button. Students can record the data they measure from the buoys, along with virtual lab results, on the Summary Data Table.

Drawing Conclusions

The "NEXT" button allows students to view a summary table of all the data they have found for any one of the four organisms and the data from all the buoys they have checked. This table allows the students to make a determination about where re-introduction of organisms will be most likely to succeed. The Submit button is not available until the students have tested all three factors: salinity, turbidity, and chlorophyll a. This information can also be recorded in the Summary Data Table.

Table 3

Of course, there are many other factors involved in any organism's survival, and if students are interested and capable they can check other sources with additional data (CBIBS website, FieldScope, EcoCheck website, Eyes on the Bay).

One important fact to consider is that the CBIBS data are gathered from the surface of the Bay, not the bottom. Measurements of certain factors, especially dissolved oxygen, can differ significantly between the surface and the bottom of the Bay.

Drawing a Conclusion

At the end of the interactive the students have to decide if there is a suitable place to re-introduce their organism, if so where, and in either case justify their answer using the data. It is important to note that there is NO RIGHT ANSWER—the data change, and what is good today may not be good tomorrow. In addition there may be no place at all, or a more than one place suitable for re-introduction.

This interactive provides students with practice analyzing real data to draw conclusions, with all its uncertainty!

To conclude this activity, students have to file a report with the PROduction Company, using their PDAs. In it, they have to synthesize the information they have uncovered through this interactive and make a recommendation to the PROduction Company as to whether or not to include reintroduction of organisms as an important part of their miniseries on the Bay. They can make their recommendation on the PDA or in the document Recommendations for Restoration.

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Teacher Tips:  Before Using the Interactive

Review the interactive yourself prior to introducing it to the class and plan to use it with your students. You may want to consider questions such as:

    • How long do you think it will take your students to complete this activity? (A good estimate is about two 45 minute class periods. This can be shortened by having students test only one pair of organisms, having different groups test different factors and share information, or using the information given in Ranges Tolerated in Virtual Lab Experiments to give students a smaller range to test)
    • What’s the best way to work with the interactive: singly? In groups? As a whole class?
    • Four different organisms in two pairs are considered in this interactive. Should each user or group be responsible for testing and drawing conclusions for only one pair of organisms? Or one organism? (The organisms are paired in the lab, but are compared to Bay data individually).
    • Each user's work is saved online, using his or her unique password. How might you take advantage of this to segment their work with the interactive to best fit your schedule and instructional needs?
    • The Summary Data Table and subsequent student answers can be emailed from the PDA or students can record their work either electronically or as a hard copy in the documents provided (Summary Data Table and Recommendations for Restoration). How do you want students to share their work with you? They can submit their answers via the PDA or on the document provided, either electronically or as a hard copy.

      PLEASE NOTE: When the contents of the PDA are emailed no identifying information is included. Please have students put their name or other identifier in the first text box they complete.

Baylab could be used in the following sequence:

    • Day 1: Students conduct experiments to gather data. At that time they learn about the different factors and how they impact the ecosystem.
    • Day 2: Check data from the Bay and draw conclusions about where re-introduction of organisms is likely to succeed. Give students time to discuss and debate either in groups or as a whole class.


This activity centers on a scientific exploration of an action that can be taken to save the Bay. If you haven't done so already, you may want to introduce the terms and concepts experimental tank, duplicate (or replicate) and control tank to your class. You can find definitions of these terms and the other terms used throughout the interactive in the glossary. Students can click on any of the terms in red to see a definition of the term in the context in which it is used. Help students understand the parts of the BayLab experiments by using Introduction to Experimental Design .

You may want to introduce this activity by talking about the reasons scientists complete experiments, the processes they follow, and the reasons for the processes. Use of real time data is an important element of this interactive. Emphasize to students that they can check back to see what the conditions are as the seasons change. In addition there are many websites where they can check these and other data gathered in and around the Bay (CBIBS website, FieldScope, EcoCheck website, Eyes on the Bay).

Because this interactive involves plant life, students should be aware that plants are producers, making their own food through photosynthesis. You may want to talk about the difference between producers and consumers before the students become engaged in the interactive. In addition the importance of algae to the Bay ecosystems, for good and for harm, is a key part of this interactive. Find more information about algae here.

You may want to introduce this activity by using a video clip available at the Cinema Bayville. The clip called "In Green Obscurity" introduces bay grasses and some of the factors that affect their abundance. "Oyster S.O.S" describes the oysters' role in the Bay, as well as the diseases and other factors that are affecting their survival. The "Chesapeake Past, Chesapeake Future" (5 short clips) introduce the various issues which are affecting the water quality in the Bay.

It may be helpful to give students a general overview of what you expect them to accomplish when completing the interactive. Consider demonstrating the site with your students before they begin working with the site. Although the site has been designed to be as user-friendly as possible, you may want to show its major activities, especially the lab sequences in the BayLab, accessing buoy data, and comparing the data sets, depending on the needs of your students.

Consider explaining to students that the experiments they will observe in the lab are representations and models of what occurs in a lab, which is representative of what occurs in nature. While as realistic as possible, the experiments may not show the complete range of occurrences that may happen if the same situation occurred in an actual lab, and certainly in the Bay.

Explain that students have to complete all the tests for an organism before they can submit their suggestion about where to re-introduce that organism. Please note that when information is emailed there is NO IDENTIFYING INFORMATION. Students should put their name or other identifier on at least one answer they email. (All information in the PDA is emailed together, so a name only has to be put in one answer).

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Teacher Tips: During the Interactive

Encourage students to use context clues in the text and use their mouse to access definitions for challenging words.

Scripts are available for the parts of this interactive which describe salinity, turbidity, and chlorophyll a. You may want your students to have a copy to help them as they complete these sections.

This Water Quality Tests document summarizes the water quality tests conducted in BayLab. It summarizes the information they receive when the factors tested are explained, and can be used for reference.

Because of the nature of the experiment and the utilization of live data, there are no "correct" answers for where to re-introduce the organisms. Find the ranges tolerated by the organisms in the interactive here . In addition guidance for the kinds of observations students should make and rubrics for scoring students' final PDA reports to the PROduction Company are also included here.

You can also use these documents to help students as they work with this interactive:

  • Introduction to Experimental Design -These questions can help your students understand the design of the BayLab virtual experiments.
  • Data Table for Tolerance Ranges - This chart allows students to record tolerance levels for the organisms they are testing as they work in Bay Lab.
  • Summary Data Table - This chart allows students to record tolerance levels for one organism and the data from the buoys to decide where reintroduction of that organism is likely to succeed.
  • Recommendations for Restoration -Students are asked to identify places re-introduction will succeed and justify their choices.
  • Extension Questions - These questions take the information in the interactive further and ask the students to consider other issues that affect the water quality in the Bay and could affect the success of re-introducing organisms.

Note that most of these documents are alternative ways to record the information recorded in the PDA while using BayLab. Introduction to Experimental Design and Extension Questions are additional resources, not contained within the interactive.

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Teacher Tips:  After Using the Interactive

What Happens After This? . . . You may want to encourage students to think about and discuss what might happen to the living creatures in the experimental tanks after they are introduced into the Bay. For example, students can examine seasonal changes in conditions by looking at data on the CBIBS or FieldScope sites. In addition there are many factors not considered here that will impact the survival of the organisms—for the bay grasses one obvious factor is water depth. How do this and other factors affect the probability of survival after re-introduction? Animals like mussels and oysters do not move once they are adults and bay grasses cannot move themselves either. Discuss what happens to the offspring of these organisms, and how the ability to move may be a survival strategy for some offspring.

Cross Curricular Connections … Contextualize the study of the Chesapeake Bay with the natural and cultural history of the region.

America in 1607: Jamestown and the Powhatan
Explore the historic Jamestown fort and the Powhatan village of Werowocomoco through this interactive feature.

The Captain John Smith Chesapeake National Historic Trail is part of the National Park Service effort that aims to connect people with the special places and stories of the Chesapeake, to help preserve those special places and stories, and to foster stewardship of the Chesapeake Bay. This website has many rich resources to help accomplish those aims.

Views of the National Parks: Chesapeake Bay offers this website as an introduction to this spectacular national treasure. Here, you can investigate the geologic events that created the Bay, see how the Bay shaped the human story in the area and how humans in turn affect the Bay's story, explore the ecology of the Bay and its shores and discover some of the many species that depend on the Chesapeake for survival.

Take Action … You may want to personalize a project by looking at things that people in your area are doing, such as the drain stenciling project sponsored by the Chesapeake Bay Foundation. A step-by-step guide to developing a classroom project is available here.

Suggestions of Classroom Projects can be found through Teaching Environmental Awareness in Maryland (T.E.A.M.) – from Maryland DNR and from MAEOE (Maryland Association of Environmental and Outdoor Educators).


Bay Grasses

The Virginia Institute of Marine Science has a website devoted to SAV which includes a number of interactive maps. They also have a webpage devoted to research on SAV.

The acreage covered by submerged aquatic vegetation (SAV, what we have called bay grasses in BayLab) in the Chesapeake Bay is shown on the chart here. It can be examined for trends and to try to correlate events such as hurricanes and other large storms to SAV levels for the years in which these events occurred. Be sure to click on the "Add SAV goal" box at the bottom of the grass to see how close we are to the desired acreage.

The disappearance of the SAV is a complex problem, and the proposed solutions are equally complex. Direct your students to research current efforts to restore Bay grasses. Start with information from the Maryland Department of Natural Resources, the Chesapeake Bay Program Virginia Institute of Marine Science and the Horn Point Laboratory of the University of Maryland, Eastern Shore.
If you are interested in participating in bay grass restoration, look at Bay Grasses in Classes from the Maryland Department of Natural Resources.


Students can examine native oyster abundance in the Bay. A chart is also available from Maryland Department of Natural Resources. Additional information on oysters in the Bay is available from the Chesapeake Bay Program, and recent research articles are available from the Virginia Institute of Marine Science.

Virginia's Oyster Reef Teaching Experience (VORTEX) is a training program focusing on the importance of oyster reef communities in the Chesapeake Bay ecosystem designed specifically for science educators by the Virginia Institute of Marine Science. Resources and further information are available from their website.

Oysters in the Classroom, was prepared by Maryland Sea Grant and correlated with teacher's resources prepared by the Maryland State Department of Education. This project offers lab experiences looking at another endangered Bay creature—the oyster. Find additional information on oyster restoration from the Chesapeake Bay Foundation and from the Maryland Department of Natural Resources. Information on oyster gardening is available from the Virginia Department of Environmental Quality. This site has links to many other sites containing information about oysters and oyster restoration.


INVESTIGATE other ORGANISMS that live in the BAY:

Horseshoe Crabs

Investigate raising these ecologically important animals in the classroom with instructions from Maryland DNR (Department of Natural Resources):


Try your hand at raising the state reptile of Maryland in your classroom. Find information from the National Aquarium, Maryland Sea Grant and from Terrapins in the Classroom, a collaboration among University of Maryland Biotechnology Institutes, Maryland DNR, and the Maryland State Department of Education.


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