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The Miracle Fish: Learning to Design an Experiment

Grades: 6-8
Author: Sandy Van Natta, Jon Valasek
Source: Original


This lesson plan leads students through the process of designing an experiment. First, students are given a miracle fish and asked to make observations. Then, through a series of steps, they develop procedures to investigate the behavior of the fish and determine the most likely cause of the curling of the fish when it is placed in the palm of the hand. After discussing the components of an experiment, students are led through a second exploration, involving polymer spikes, where they practice and build on what they have learned by forming questions, identifying variables, making observations, collecting data, completing graphs, and drawing conclusions.


What should students know as a result of this lesson?

  • Students should know the difference between an activity and an experiment.

What should the students be able to do as a result of this lesson?

  • Form a hypothesis
  • Write a testable question
  • Identify independent and dependent variables
  • Identify controls
  • Write a simple procedure
  • Collect and analyze data
  • Draw a conclusion based upon the data collected


Miracle fish One per person. Order from by typing in the search block: “plastic fortune fish”. The order number is SP-39/761 currently (8/05) $7.95 a gross.

Growing spikes One per group. Order from as “water gel spikes, GB-3” currently (8/05) 10 spikes for $2.50. or call JRM Chemical at 1-800-962-4010 and ask where you can buy Soil Moist clear plant spikes. JRM supplies stores like ACE Hardware but does not retail their products.

Plastic bags One per group. Reclosable sandwich bags that can hold 250 mL of water.

Pickling or Kosher salt Enough to supply each group with one tablespoon of salt. Use pickling or kosher salt because it does not contain the additives of normal table salt that will cloud the water.

Distilled water or normal tap water as desired. 250 mL per group.

Paper towels

Heat source Heating pad, window sill, lab heater. The number needed depends on the size of the group.

Small boxes to isolate fish in darkness.

Oil Mineral oil works well, use a small amount as necessary

Graph paper – 1 sheet per group



  1. Take the fish out of the plastic sleeve and place it on the palm of your hand.
  2. Observe the fish for at least 1 minute and record your observations on a data sheet. Use your sense of sight, touch, smell and hearing when making observations. Taste should not be used in this activity. Sort your observations according to your own criteria.
  3. Share some of your observations with the group as a whole.
  4. Since you have just observed a unique phenomenon, the curling or dancing of the fish, try to form hypotheses to explain your observations related to the motion of the fish and share these with the group after recording the hypothesis on a data sheet.

Assessment The teacher listens to the oral responses of the students and notes if they used several senses to make observations and were able to categorize their observations in some way – such as observations relating to the appearance of the fish and those relating to the behavior of the fish. The hypotheses formed by the students should relate to the curling or motion of the fish.


  1. How do you think you can discover which hypothesis supports your observations? Will you have to change one of the factors affecting your fish? Record you idea on the data sheet.
  2. Which factor or variable might you wish to test or change? Record your idea.
  3. If you change this variable, what will you want to observe in response to your change? Record this idea also.
  4. Based on your responses to steps 2 and 3, write a testable question that will allow you to set up an experiment to test your hypothesis. Write your question in the following form: “How does ________ affect ______?
  5. What would you want to keep the same throughout the experiment so that any changes in the fish can be accredited to the variable you changed? List these on the data sheet.
  6. Write a simple procedure to test your question.
  7. Share your procedure with the entire group. Not all groups may be testing the same variable or have the same procedure.
  8. If your procedure is approved by the teacher, conduct your experiment, make observations, and record your observations. Share your observations with the group as a whole. Using all the observations made by the class, draw a conclusion based on all observations.

Assessment In the Exploration phase, the teacher can note whether or not the learner was following procedures, collecting and recording data, and working in a logical form.


  1. Explain what you learned in this activity both about experimental procedure and about the behavior of the fish.
  2. You had to change one variable and then observe the response of the fish during the course of your experiment. The variable changed by you is known as the independent variable. The dependent variable was what they observed or measured in response to that change. Please label the independent and dependent variable in the original testable question you wrote.
  3. There were certain factors that were kept the same in each experiment. These factors are known as controls. Label the list of things you kept the same throughout the experiment as the controls.
  4. How do you think an experiment differs from an activity? Write your answer on the data sheet.

Assessment During this phase the teacher can use questioning techniques to asses the students’ comprehension of new vocabulary and concepts. Also, a rubric can be designed to see if students used the proper terminology and logic to explain their results.


Note: Depending on whether or not balances are available to you, select either to mass the spikes with balances or measure the length of the spikes with metric rulers.

  1. Obtain a spike made out of the superabsorber, polyacrylamide. Water diffuses in between the strands of the polyacrylamide that causes the polymer to swell and hold water. These spikes are the ones used by gardeners to water and fertilize plants. The most familiar superabsorber is sodium polyacrylate, a polymer found in diapers. It can hold 600 times its weight in distilled water, but this capacity is diminished when urine or substances containing sodium come in contact with it
  2. What factors do you think may affect water absorption of the spike?” List your ideas on the data sheet.
  3. Do you think different amounts of water will be absorbed by the spike in different types of water? How would impurities in the water affect its absorption? Share your answers with the class.
  4. Identify the variables that you could change to test water absorption. List these on your data sheet but select just one variable you are interested in testing and share your ideas with the class. Would this be the independent or dependent variable?
  5. Identify a characteristic of the spike you could measure. Remember you are limited to the resources selected at the materials list. Is this your independent or dependent variable?
  6. Identify variables that need to be controlled or kept constant in order to accurately determine water absorption of the spike. What are these variables called?
  7. Now that you have explored the things you could change, measure, or keep the same, write a question that would test the spike’s water absorption capability.
  8. Share your questions with the group. Working with your teacher, select one question which the group will test.
  9. Write a procedure for testing the chosen question.
  10. Design a data chart for collecting your data. Be sure to include a column for % growth of your spike. Calculate percent growth by dividing final length or mass (that you recorded at 24 hours) by initial length or mass and multiply by 100%.
  11. Conduct your experiment and collect your data over the next 24 hours.
  12. Now that you have collected data, what do you think you can do with it? Share your answers with the group.
  13. Graphing is one way to show patterns in data and allow the viewer to make predictions. A graph should have a title, X and Y axis labeled and appropriate units included. Intervals are equal but independent of the other axis. The independent variable is usually placed on the X axis. The dependent variable is placed on the Y axis. Draw a bar graph using the data you have collected.
  14. Using your graph as support, what conclusions can you draw from the data?
  15. Is any of the data you received not what you expected or “out of the ordinary”? If so, why do you think this might have happened?
  16. List any sources of error you might have encountered during the experiment.

During the final Elaboration phase, the application of the learner’s knowledge to the new “problem” can be considered the “test”. If students have written a testable question, identified variables, designed a procedure, collected and analyzed data to draw reasonable conclusion, then they have successfully applied the skills taught in this lesson.



Best Teaching Practices

  • Hands-on Teaching
  • Questioning
  • Inquiry
  • Learning Cycle

Alignment with Standards

NGSS Standards:

  • MS-PS1-3 Gather and make sense of information to describe that synthetic materials come from natural resources and impact society.
  • MS-PS1-4 Develop a model that predicts and describes changes in particle motion, temperature, and state of a pure substance when thermal energy is added or removed.
  • MS-PS2-2 Plan an investigation to provide evidence that the change in an object's motion depends on the sum of the forces on the object and the mass of the object.

Common Core Standards:

  • RST.6-8.1 Cite specific textual evidence to support analysis of science and technical texts.
  • RST.6-8.3 Follow preciesly a multistep procedure when carrying our experiments, taking measurements, or performing technical tasks.
  • WHST.6-8.2 Write informative/explanatory texts, including the narration of historical events, scientific procedures/experiments, or technical processes.

National Standards:

  • Content Standard A: 5-8 Science as Inquiry
  • Content Standard B: 5-8 Physical Science

Ohio Standards:

  • Grades 6-8 Scientific Inquiry Benchmark A and B
  • Grades 6-8 Physical Science Benchmark A
  • Grades 6-8 Scientific Ways of Knowing Benchmark A

Content Knowledge



No special safety precautions are needed. The "Miracle Fish" can be replaced into its original plastic package and reused. The water absorbing spikes can be placed in the trash. The salt water can be poured down the drain.


Superabsorbers are found in diapers and water absorbing products for plants. They are also found in chemical spill kits and even blood coagulation and disposal kits in surgery. Student may research the use of superabsorbers in products found in daily life.


See Learning Cycle

Other Considerations

Be aware of students' abilities and ethnic backgrounds when choosing groups. Try to place students of varied abilities and backgrounds in each group. Each student should be given a task or job in the group. One student obtains all the materials, one can record all information, one can be in charge of the actual data gathering and one can be in charge of clean-up.

This activity will take at least 2 class periods.

Printable PDF Worksheets

For student appropriate fortunes: Worksheet - created by Mary Vasek.