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Where Did the Water Go?

Grades: 5-8
Author: Dr. Kathie Owens
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Module Description

As a result of the presenter-conducted discrepant event demonstration, teachers will pose a problem. They will formulate their hypotheses, conduct experiments, and report their findings. Since it is unlikely that the teachers will be able to reproduce the outcome of the demonstration, it will be pointed out to them that very often scientific investigations do not lead to "answers". We suggest that this experience follow the lesson: "Miracle Fish: Designing a Scientific Investigation". This lesson gives teachers an opportunity to experience and discuss how a demonstration can be a vehicle for investigative science activities.


  • Participants will explain that most scientific investigations proceed along organized approaches, frequently called scientific methods.
  • Participants will pose a testable question, formulate a hypothesis, conduct an experiment, gather, process and analyze data, and report findings.
  • Participants will discuss the use of demonstrations and discrepant events as vehicles for teaching science.
  • Participants will design and implement in their classrooms a lesson on using a demonstration or discrepant event as a prelude to scientific investigation.


  • Participants will pose a testable question, formulate a hypothesis, conduct an experiment, gather, process and analyze data, and report findings.
  • Participants will experience how a discrepant event can precede scientific methods of investigation.


Cost: The materials for this lesson should cost less than $10 because most of the materials are everyday, common items.

For the Provider of Professional Development(PPD): three identical, opaque cups; small quantity of sodium polyacrylate (AKA WetLock); water. Sodium polyacrylate is available at low cost from suppliers of science equipment and chemicals. It is one of the super absorbent chemicals in baby diapers. Do not shred diapers to extract the chemical as there is a possibility of release of the fibers into the air and subsequent inhaling of this material could be dangerous to one's respiratory health.

For each group of 2-3 participants: opaque cups identical to the presenter's cups; absorbent materials (for example, paper towels, cotton balls, shredded paper, sponges); water

Suggestion: Give each participant a small amount of sodium polyacrylate in a small container (for example, a 35mm film container) or small baggie. Provide a copy of the MSDS (Materials Safety Data Sheet) for each participant. Download a copy of the MSDS at


Conduct the demonstration/discrepant event as described in the lesson: Where Did the Water Go?. Demonstrations should be conducted as "show 'n discover" rather than "show 'n tell" events. That is, the presenter's questions should advance the demonstration, participants should record observations of the phenomena, and teachers should say more and do more than the presenter. DO NOT REVEAL TO THE PARTICIPANTS WHAT IS IN THE CUP!

Since participants must test their hypotheses and follow your procedures in the next section, you might want to have a second set of cups prepared to conduct the demo a second time. Taking video footage of the event and replaying for a closer look at the procedures will assure that participants are following your procedures more closely than if they were remembering exactly what you did.

For the exploration (experimentation) section, put the participants into small working groups. Each group should develop its procedures to do an experiment to test each of their hypotheses. Or, if time is limited, each group can test only one of their hypotheses. Be sure that all hypotheses put forth by the participants are tested. Since members of the scientific community would repeat tests to see if findings hold up and to verify results found by colleagues, participants in one group should conduct experiments done by members of another group. Make sure that each experiment is done more than once and that each test employs exactly the same procedures.

Groups should share their findings for the large group to hear. The presenter should be careful not to use words like "solution, answer, incorrect or correct findings" in responding to participants' reports of their experiments. Include "following exact procedures" in the discussion; scientists must not only use the same materials but also follow precise procedures when attempting to replicate each other’s experiments. More appropriate follow-up responses/questions include, How does your conclusion align with your data? Or, if you had a chance to perform another experiment to test your hypothesis, what would your design be?

It is likely that no group will be able to reproduce the outcome of the presenter's demonstration. Discuss the reality that "nothing happens" is often a result of scientific studies. "No findings" IS a finding! Sometimes scientists work for many years to support or do not support their hypotheses, but end up with apparently "no results". Science has many unanswered questions. Emphasize the nature of science and its tentative findings. Be cautious about using "prove" when discussing scientific methods; science is more about finding evidence that does or does not align with a proposed explanation (i.e. hypothesis).

Have a discussion about how to conduct demonstrations in the science class (see above) and what makes a worthwhile discrepant event (see rationale). Suggested questions: What are some characteristics of a demonstration? When might the use of a demonstration by the teacher be preferred over experimentation by the students? (for example, when supplies are limited, when materials are hazardous, or when step-by-step directions may be needed).

Instead of using the elaboration portion of the lesson for students as part of the participants' learning experience, we suggest that time be allotted for planning classroom implementation activities. For example, if the teachers wish to teach this lesson to their students, the presenter should refer the teachers to the source of the lesson and should reveal the contents of the "mystery" can.

Classroom implementation: Have the teachers plan a lesson using specific methods and conducting a demonstration or a discrepant event using one or more activities illustrating Bernoulli's Principle. See Principle/bernouli_s_principle.html for examples.

Each plan should include: learning goals for students, materials needed, safety concerns, activities done by the teacher, activities done by the students, and an assessment of the students' learning. See the Lesson Plan Template located below.


Although discrepant events frequently take the form of demonstrations, all demonstrations do not necessarily include discrepant events. Discrepant events can be built into hands-on activities that students actually perform. A detailed description of discrepant events as a teaching technique can be found at

Science Standards

Content, Technology, and Professional Development:

NSES Content - Science as Inquiry: All students should develop abilities to do scientific inquiry (Content 5-8)

NSES Professional Development - Professional development for teachers of science requires learning essential science content through the perspectives and methods of inquiry. Science learning experiences for teachers must involve teachers in actively investigating phenomena that can be studied scientifically, interpreting results, and making sense of findings consistent with currently accepted scientific understanding.

Best Teaching Practices

  • Inquiry
  • Discrepant Events

Time Frame

One-two hours based on variations in the procedures (see procedures).


Out of sight of the participants, put about a teaspoon of sodium polyacrylate in the bottom of one of three identical opaque cups.

Have a supply of water at hand (a pitcher, for example) and, for dramatic effect, a heavy absorbing towel.

Gather materials for particpants' experimentation.

Prepare take-home containers for the participants (see materials).

For ease of distribution and clean-up, put each absorbing material in its own plastic bag or container (for example, dishpan).


For the Provider of Professional Development (PPD): Sodium polyacrylate is not considered a hazardous chemical, but the PPD should use care not to inhale this powder. If sodium polyacrylate gets in the eye, the eye will become dry and irritated. For disposal, mix the sodium polyacrylate with a couple of tablespoons of salt and wash the mixture down the laboratory/site sink with plenty of water. The dry powder or the gel can safely be put in the trash. Download a copy of the MSDS at

For the teacher-participants: There are no safety issues related to this lesson. However, if this lesson is implemented in the classroom, the teacher will need to stress to the students that any absorbent materials used to test their hypotheses should be handled carefully and responsibly.

For a comprehensive discussion of laboratory safety, please see the safety information at Flinn Scientific Company


Throughout the lesson, assess participants' learning using suggestions from the lesson for students.

By your actions (asking questions, monitoring the participants' work, giving time for participant-talk) model for particpants the assessment techniques they should use in their science classrooms. Ask the participants: In what ways was the PPD doing assessment during this lesson? How can science teachers use these ways of assessment in their classrooms?

Ask the teachers to share (orally or in writing) an example of a science demonstration they do in their classrooms. Have them explain why they conduct this activity as a demonstration and what scientific methods are employed in the demonstration.

Check the teachers' implementation lessons for the presence of the features listed in the procedure part of the teachers' lesson. If possible, visit the science classes when the teachers are teaching the lessons developed at this professional development session.

Explanation of Science

Note: More information about the development and uses of sodium polyacrylate is provided for the PPD as background information or in case participants ask questions about the absorber. This information can be found at: This information is not relevant to the lesson and should only be shared to answer participants' questions.




As an extension, participants could research and discuss the suggestions in the elaboration portion of the lesson Where Did the Water Go?.

Lesson Implementation Template

Download Lesson Implementation Template: Word Document or PDF File


In this experience model strategies for meeting the needs of diverse learners. As examples, be sure participants are seated where all can see the demonstration. Compose groups with diversity in mind.


None available for this module


Where Did the Water Go?