Description

A flask, capped with a rubber stopper and glass tube and partially filled with water, is heated and then inverted into a beaker of water—the water in the beaker rushes up and into the flask. Students propose theories and gather data to investigate them. A few classroom students will share responses during the QuickTime movie demonstration.

Materials

No materials are required.

Leading the Activity

In the QuickTime movie, the distance learning instructor demonstrates the discrepant event, poses the focus setting question: "Why does the water rush into the flask?" and solicits responses from the students. Discuss the activity with students encouraging them to observe carefully and discuss observations with precision and specificity. Students can share responses with Gary in the online discussion group.

Inquiry Teaching Strategies

1. Encourage the students to observe and discuss the inquiry problem.
   
2. Place the responsibility for the solution on the students.
   
3. Solicit responses from students, including: theories ("I think...because..."), requests for data ("Is the flask still hot when you take it off the..."), reporting of data ("The water waits a few moments before it..."), and so on. Encourage and assist the students to work on the problem.
   
4. Encourage students to make careful observations and order them in sequence.
   
5. Remind students to use precise language—draw attention to examples of specific and precise communication exhibited by students.
   
6. Allow time and opportunity for students to work on the problem as a class without telling them the answer.
   

Teacher Background Information

As the water and air in the flask are heated they expand. The air in the flask expands and can no longer be contained in the flask and some is pushed out the mouth of the glass tube—this cannot be easily observed. As the water heats, some of the liquid turns to a gas and begins to fill the flask above the liquid. As more and more liquid turns to gas, we can easily observe the steam escaping out the mouth of the tube. When the flask fountain is inverted into the beaker of water, the water (liquid and gas) continues to expand. We can observe the liquid (now in the neck of the flask) being pushed out of the flask. This is a "step" in the observations that may be overlooked by students. When the flask fountain is removed from the heat it cools and the contents contract. This contraction creates less pressure within the flask compared with the air outside the flask (a partial vacuum). The greater air pressure outside the flask forces the liquid back into the flask. If there is a dramatic difference in the pressure inside and outside the flask, then the water will rush into the flask as it cools. If the flask cools slowly, or if the difference in pressure is not great, the water will rise in the flask more slow

Range of Results

It is likely that students will respond with many theories about the problem without suggesting ways of generating data to support their ideas. Whenever possible, allow time and opportunity for students to realize for themselves that additional data is needed and that they must determine how to generate that data. As students have additional practice with inquiry problems, they may begin to propose data generating activities more readily. It is possible that students will be uncomfortable with inquiry problems. They may ask you to solve the problem for them, or validate their ideas and data. Resist the temptation to provide "free data" or otherwise prompt the students. Remind the class that it is up to them to decide what new data is needed, how to obtain that data, what data to trust, if their ideas are correct, and when they are satisfied that they have solved the problem.

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Notes on the Inquiry Teaching Strategy

For further discussion of inquiry, student discovery, and constructivism, here are some general notes:

Accept all data answers.
Students are encouraged to share observations (data) with other classmates. All observations should be accepted without judgement. If a student reports data which seems incorrect, do not contradict the student. A good response is simply: "Thank you for sharing." In many cases another student will have differing observations to share. When the reported data do not match, students can be encouraged to observe the activity a second time by playing the QuickTime movie of the demonstration again. Allow the students to realize for themselves that observations or assumptions may be incorrect.

Accept all theory answers.
Students are encouraged to share theories about the discrepant event. All theories should be accepted without judgement. Establish a climate in the classroom that is "safe" for students to take a risk and share ideas and propose data generating activities. Encourage students to exercise fluency of thinking by considering many ideas which might accommodate the observations (data).

Encourage data generating responses.
Generating data is often difficult for students. Teachers should encourage students to think of and respond with data generating activities. These might include an experiment which might test a theory, asking questions, and reference sources of data (books, etc.).

Observe students for evidence of inquiry skills. Observing students while they work on inquiry problems can provide the teacher with valuable information about their students. Watch for student language and behaviors which indicate growth in inquiry skills.