If the instructor can allot no class time:
The students can benefit from the audio through independent study. Students visit the exhibit online and perform the exercises assigned by the teacher. For example, one exercise can be chosen and given to the entire class. Or different exercises can be assigned by the first letter of the student's last name. Or, as a third alternative, a group of exercises can be offered and each student can choose which avenue to explore.
If the instructor can allot one class day:
Students can visit the exhibit as a group during class time. In this case, scripts should be available to every student or pair of students. Permission is granted to the instructor to make photocopies of the text for the purpose of providing every student or pair of students with a copy for classroom use. Students may be given one homework assignment prior to listening to the audio and one after listening to the audio.
The uninterrupted audio track and all the rest of the unit can be purchased at nominal cost on a CD-ROM which can be played in class or made available to individual students who have access to a computer.
Most teachers will probably find the above the best way to use the unit.
Or Teachers may elect to have students view the exhibit independently (see above) and later use class time for discussion and exercises.
If the instructor can allot two class days:
DAY 1: Students view the first half of the exhibit. The remainder of the class is used for comments on one or more discussion questions, such as those in the accompanying list.
A homework assignment should be chosen, for example from the accompanying list, reflecting teacher or student interest.
DAY 2: Students view the second half of the exhibit.
The beginning of the class may center on reviewing homework or on fresh questions chosen by the instructor. The remainder of the class time may be spent on discussion questions emphasizing the exhibit as a whole.
Homework should be assigned. This might require the reading of an article included in the unit, or library research.
The 5E Model
The 5E model of good science instruction recommends that teachers structure the lesson so that it includes the following components: engage, explore, explain, elaborate and evaluate.
In using the Pulsar Discovery exhibit, teachers can adopt the 5E model in the following manner:
Engage: Students should be questioned about the size of astronomical objects like the Moon, Earth, Sun and other stars. Students at the high school level can still be expected to harbor misconceptions concerning the rotation and revolution of the Earth, no knowledge of the rotation of the Sun, and little knowledge of how the solar system is held together. The questions of scale can engage students and provide a basis for a better appreciation of the pulsar. Without such a preliminary discussion, students will not understand why the discovery of the pulsar came as such a shock to scientists the world over. Students should be given the opportunity to articulate their prior conceptions. Teachers should be attentive to the students' understanding so that the subsequent instruction can provide a rationale for students to continue their prior beliefs or to replace them based on their study.
Explore: Students can read and listen to the script and begin to explore the events leading to the discovery of the optical pulsar. They can continue their exploration by responding to some of the exercises including the brief laboratory activities on the use of a manual stroboscope and the creation of a diaphragm. They can also review the notes that Disney recorded on the night of the discovery.
Explain: Students should study the articles that are included in the exhibit. The original research articles may be a bit difficult in their entirety but should be attempted. Science students get too few opportunities to read any original literature. The other articles and essays were chosen as part of the exhibit because of the different perspectives that they bring to our understanding of pulsars.
Elaborate: Students should have the opportunity to apply the knowledge from the script to new situations. Students should review the Table of Contents from a Crab Nebula symposium held just a few years after the discovery of the first pulsar. They can complete exercises related to the physics of pulsars as well as exercises related to the tape recording, the interaction of the scientists, and the scientific processes that were used to insure that a mistake had not been made.
Evaluate: Many of the exercises can be used as evaluative tools of what students understand and are able to do. The teacher should help students set the criteria for successful achievement. What is the level of expectation in terms of the physics problem solving or the related research items? Evaluations can also include group projects that require students to produce informational pamphlets, to perform or create additional physics simulations, or to compose an essay or play that draws out the human and scientific elements in the pulsar discovery.
The 4 Question Model
The 4 Question model of science instruction requires that students be able to answer the following questions:
- What does it mean?
- How do we know?
- Why do we believe?
- Why should I care?
In using the Pulsar Discovery exhibit, teachers can adopt the 4 Question model in the following manner:
What does it mean? Students should be able to provide a sense of the size of the pulsar and the rotation rates of the pulsar. They should also be able to explain the decrease in the rotation rate using conservation laws. They should also be able to explain the content standards of the National Standards in the domains of inquiry, technology, society and history.
How do we know? We know because we made observations. How were Cocke and Disney able to measure the rotation rate of the pulsar? How were they sure that their data were accurate? Why was it important to know the expected period of 33.2 milliseconds before beginning the experiment? How would the experiment have changed if they did not know the period from the outset?
Why do we believe? Why do we believe that the pulses are naturally occurring and not the result of an extraterrestrial being trying to contact us? (The first pulsar was initially suspected to be such contact.) The size of the pulsar demands that the origin be a neutron star. The models for stellar evolution must allow for the incredible compression of matter. Calculations of forces, stellar evolution, conservation laws and a mechanism for explaining our observations must all hold together if we are to believe in the optical pulsar results.
Why should I care? The pulsar has very little relevance to our lives. Similarly, the electrical investigations of Faraday, Ampere, Maxwell and Hertz had little relevance at that time. If scientists like those mentioned had been required to work on improving modes of communication, the discovery of radio waves and the electromagnetic spectrum would probably not have occurred. Their interests and investigations led to the development of radio, television, and the transistor along with all of the accompanying social changes. There are similar examples of pure research into the behavior of atoms leading to discoveries that found applications in MRI and other medical technologies. Who should decide what research should be funded? Why should we care about pure scientific research?
A word to the wise
Physics teachers may well lack experience in leading discussions. We all
know, however, that it is not possible nowadays to think about science
without taking account of different viewpoints on social questions. Since
the interaction of science and society is often taught only superficially
in social studies courses, science teachers need to explore the issues.
It is recommended that teachers have a number of discussion questions
created or chosen from those provided, so that if one does not develop
into a useful class dialogue, a second or third question can be presented.
History teachers frequently lack experience with science demonstrations, problem solving, or explanation of scientific theories. We all know, however, that the citizen can no longer separate understanding of modern history from basic ideas about science itself. Since many students have a very rudimentary science education, a unit in the history of science may be one of their few encounters with scientific reasoning, and it is important to be sure they can follow the logic of the science itself. It is recommended that the instructor test a demonstration before presenting it to the class. Similarly for science problems, a previously worked out solution or explanation will always lead to a better class presentation.
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