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Fish Farm: an open ended, student centered laboratory activity

By Thomas E. Manerchia

This activity was modified by Thomas Manerchia from a shared activity presented by Cynthia Mannix, L a Jolla, CA. at the 1994 Woodrow Wilson Institute in High School Biology

Type of Entry:

  • unit
  • class activity
  • project

Type of Activity:

  • Hands-on activity
  • Inquiry Lab
  • Group/Cooperative Learning

Target Audience:

  • Life Science
  • Biology
  • Integrated sciences
  • Environmental studies

Notes to Teacher:

(Located after activity)


This activity has been developed in order to provide students with an open ended problem to solve over an extended time period. The goals are to promote critical thinking skills, team work skills, scientific problem solving skills, computer literacy skills, and time management skills. It is intended that this exercise run concurrently with the standard Biology curriculum. It can be extended throughout an entire semester if need be. Students are told that we have been contacted by a fictitious company which raises tropical fish in order for us to do some basic research for them so that they might keep their production costs down. They need to know the optimum salinity in which to hatch the brine shrimp that they use for food. To do the above students are required to design, write and carry out an original laboratory protocol to determine the best salinity in which to hatch the brine shrimp.


This activity is designed to teach students how to analyze a problem; design and carry out an original laboratory procedure.

It is required for students to work in teams to teach cooperative/group learning. It is also necessary for them to meet outside of class time for planning sessions once the project is underway.

The preparation time by the teacher simply requires that the time schedule plan be thought out and that the laboratory space be made available for an extended period of time. The equipment and materials needed for this activity are minimal.

The class time required can be arranged at the discretion of the teacher. It is recommended that at the beginning of the exercises several entire classes be devoted to the exercise. After that, partial classes can be devoted to the project on a scheduled basis. Whenever the activity requires class sharing, entire class periods will have to be used. But the project can be spread out over a semester if need be.


The Fish Farm--an open ended, student centered laboratory activity

This activity has been developed in order to provide students with an open ended problem to solve over an extended time period. The goals are to promote critical thinking skills, team work skills, scientific problem solving skills, computer literacy skills, and time management skills. In my course, this exercise ran concurrently with the standard Biology curriculum for nearly 3 months.

Preliminary Phase:

This takes several days but is an important step. I begin by asking the students to form teams and write what they feel is a scientific lab procedure to answer a question/problem that I have asked about photosynthesis. You could choose any convenient topic to do this. Each group submits a written lab procedure. Then I photocopy all of the procedures and hand them out. As a group sharing exercise, the class critiques each of the procedures. Following that, I ask each of the groups to again try to write a scientific laboratory procedure to solve the same problem. This develops a sense of purpose and allows students to enter the actual activity with an understanding of variables, controls, sample sizes and data collection.

To begin the actual exercise, students are told that we have been contacted by a fictitious company which raises tropical fish in order for us to do some basic research for them so that they might keep down their production costs. They want us to find out the best percent salinity in which to hatch the brine shrimp which they hatch to feed their fish. I deal with only a single variable, salinity, but the activity could incorporate more variables. Students are divided into teams of 3 or 4 and not given any information as to how to approach the problem .

Phase 1:

Research on brine shrimp. This can include library resources, community resources, teachers , computer and internet resources, or any possible source of help in order to teach students to recognize how information can be gathered. When dta has collected, class sharing sessions are used to reinforce the value of gathering and managing this information to solve a problem. The teams must decide how to best use all this information. All records are kept in a lab journal.

Phase 2:

Each team of students must write a lab procedure to solve the problem. I have multiple meetings with each team to discuss and grade each rewrite of their proposed procedures. Each team must go through several rewrites as I continue to meet with them. I never tell them how they should do things, but I pose questions for them to consider. They make all the final decisions.

Phase 3:

Each team carries out the laboratory protocol exactly as they have designed it. You will need to build in much flexibility so that many different kinds of approaches can be tried by different teams at the same time. Also anticipate failures and restarts by individual teams. The three biggest problems encountered were elimination of variables, counting eggs, and making exact percentage salt solutions. Most eventually find a chemistry teacher to use as a resource for the salt problem. Allow them to plan and carry out some things which could not work; this is crucial to spirit of the exercise.

After the first experiments are run, we again have a general class debriefing and share thoughts and approaches as we did in the preliminary exercise. This is helpful for the teams to formulate better ways to solve the problem than they have already tried. A second round of protocols is written and a second round of experiments follow. It can take several rounds before some students really discover how to do the work well. By this time different student teams are on different time schedules. But all eventually get to...

Phase 4:

An analysis of the data and writing a formal lab report which includes a graphical analysis. When each team has decided that they have answered the question posed as best they can, they call an end to their experiments. I require that this phase be done on the computer and turned in on disk to reinforce computer skills. I discuss formatting of a report with them and review the basic computer skills necessary before they actually write the report.

The final step of the activity is a general debriefing, focusing on the processes of critical thinking and scientific method to reinforce those concepts.

Notes to Teacher:

  1. Most students are surprised when they see brine shrimp eggs for the first time. Counting them out or developing a technique for sample size is a real challenge. There are some ingenious solutions that surface. If you have trouble I suggest a volume technique using capillary tubes to set a sample size. Some students will insist on counting each individual egg. They can learn something about time management here.

  2. Experimental volumes: The first round of experiments quickly teaches most students to reduce the volume used to a very small one. The most favored reaction vessels were small test tubes. This of course means that you can conserve lab space when many teams are involved. Some also used small plastic cocktail glasses.

  3. Counting hatched shrimp is also an area where considerable practice and thought enter the picture. Some suggestions that my students came up with were pipetting droplets onto saran wrap and counting the shrimp in each droplet, or using petri dishes with quadrants drawn onto them. Hand lenses or dissection microscopes work well.

  4. The supplies are easily obtained through the standard biological supply houses. The only expense should be the eggs and some marine salt.

  5. I suggest setting a time limit for hatching to try to standardize this across the teams. I used three days.

  6. You will need some balances for measuring out salt in order for the students to create the correct percentages of salt solutions.

  7. Solving each of the problems as they surface is really part of the process of doing science, so let them do things even if you know they are wrong. I had some salt solutions made that looked like slush.

  8. Patience and communication on your part will keep each team rolling along. Keep in mind it is not going to be done in a few days. Also keep in mind that it is the process that is important in this exercise, not the brine shrimp, themselves.

  9. As a follow up, you might have them suggest more refined techniques based upon what they have learned.

  10. It is also possible to insert various skill building activities between the main phases if the student population needs some extra help with concept or techniques. These can be chosen and used at the discretion of the teacher. Some student populations would not need any, others might need more help to keep going.

  11. In this exercise there is an enormous amount of flexibility in focus and timing and emphasis that each teacher can employ in order to best suit his/her schedule and school situation.

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