Introduction and Organization

Astronomy Today, 7th Edition Instructor Guide

Introduction and Organization

Introduction and Organization

Welcome to the Instructor Guide for the 7thedition of Chaisson and McMillan’s Astronomy Today. Earlier editions of this Instructor Guide (formerly called the Instructor Resource Manual) were prepared by Dr. Leo Connolly of the Department of Physics, CaliforniaStateUniversity, San Bernardino, California and Steven R. Murrell of the Department of Physics, HenryFordCommunity College, Dearborn, Michigan.The current edition incorporates much of their earlier work, and many of their excellent ideas, teaching suggestions, and problem solutions have been retained in the text of the current manual. This and earlier editions have also drawn heavily from the Instructor Resource Manual that accompaniesChaisson and McMillan’s Astronomy: A Beginner’s Guide to the Universe. Written by Judith Beck of the University of North Carolina, the manual provided the inspiration for the format of the chapters in this guide,and many of her excellent and insightful recommendations and ideas have been incorporated throughout.

This Instructor Guide is designed to help you, the instructor, organize your thoughts and materials for classroom lectures and activities. You will find that the chapter layout is designed to match that of the textbook. In each section you will find the following:

• Achapter outline
• Asummary of chapter contents
• A list of major concepts in the chapter
• Some lecture and demonstration suggestions
• A list of lecture-tutorials relevant to the material
• Some student writing questions, to stimulate thought and discussion
• Answers to the end-of-chapter Review and Discussion questions and Conceptual Self-Test questions
• Solutions to the end-of-chapter problems
• Suggestions for materials that might aid in your class discussions
• A list of websites, books, and magazine articles pertaining to the textbook chapter content, to help you and your students gather more information.

Teaching Introductory Astronomy

It is very likely that the majority of your students will be non-science majors who are taking your class to fulfill a required course credit.You may even want to poll the class at the beginning of the semester about their motives, to confirm that this is the case.Even though they may be non-science majors, they are still taking your class to learn science.Stress to them early on that this is not a course on astrology, nor will you be watching old Flash Gordon movies!All semester, you should keep in mind that your class may not only be the first science class your students have taken, it may well be the only one they will evertake!

Astronomy is a fantastic class to introduce students to science, for many reasons.Astronomy is a very popular discipline, as evinced by the many popular magazines and websites about astronomy.Astronomy is a very visual science: the images please the eye as well as stimulate the imagination.Many of the objects discussed in the class can be observed fairly easily by most students.Students may never see a particle accelerator or an electron microscope or a tropical rain forest in their lives, but they can look through a small telescope and see the moons of Jupiter!Like all sciences, astronomy is constantly changing and evolving; what sets astronomy apart is that many of these new discoveries can be understood by the novice.If you have used the previous editions of the textbook, you will find quite a bit of new material in this edition.

To a great degree, the “level” at which you teach this class will depend on the amount of mathematical rigor you demand of students.Approaches can vary, from removing all quantitative material to incorporating extensive computation and graphing.All of these approaches are valid, and the course you choose should depend on your students and your own philosophy.Just remember that if many of your students are non-science majors, they may be afflicted with the dreaded “math anxiety,” and you will have to work much harder to help them out!

One way to help students who are intimidated by equations is to present them as a form of “shorthand.”Some people say that mathematics is like another language, and they are absolutely correct!Mathematical symbols are essentially a shorthand notation to communicate the relationships between variables.You may want to emphasize this characteristic of equations, and guide students through the “translation” of an equation into a statement of relationships.Practice is very important as well.Be careful of doing too many examples in class – after a certain point, students will not get any better at working problems by watching somebody else work them.You may want to ask students to work on some sample problems in groups, to teach each other how to solve problems.On my class website, I present examples of worked problems for every equation I expect students to use.However, instead of just presenting the entire worked problem at once (which would be just as ineffective as working it on the board), the site compels students to click through the individual steps in the problem solving process, with instructions to try and work out the step before they advance to the next step.This provides students with a model that they can work through step-by-step.Examples can be found on my course website, located at

Probably the most important thing in your class will be the energy level – of you and your students!Many students enter an introductory astronomy class already fascinated by the subject, even if they do not yet know much about it. Capitalize on their interest and enthusiasm! In teaching astronomy, you have the opportunity to present some of the most bizarre, immense, baffling, and complex structures and ideas in science. Challenge your students to engage with and question these ideas. Present the study of astronomy as a human endeavor, as a quest for understanding, and as an enriching, exciting experience. If you have high expectations, your students will reward you by rising to the occasion!

Teaching Techniques

LECTURES

In recent years, many education specialists have taken the position that lecture is not an effective way of teaching.These detractors maintain that lectures cannot hold students’ attention for more than 15-20 minutes, and that long-term knowledge cannot be achieved through lecture. Despite these condemnations, it remains a popular delivery method, due to a number of factors: large classes, large amounts of material to cover, lack of instructor experience with alternative methods, institutional culture, etc.My experiences in 20 years of collegiate instruction have shown me that a well-delivered lecture can be effective at keeping students engaged and learning.A bad lecture will be ineffective, but that can be said of any teaching technique!

Although it may seem to go without saying, it must never be forgotten: when you are giving a lecture to students, you are not giving a presentation to other scientists!The elements that often make for a good presentation at professional conferences lead to very poor lectures in a classroom.During a conference talk, your audience is paying attention to the facts and figures and ideas you are presenting.In the classroom, for better or for worse, students are paying attention to you.Even something as simple as changing your position in the room or the inflection of your voice can make a difference in holding students’ attention.

The formal tone of a presentation is counterproductive in a class lecture; a good lecture is a conversation between the instructor and the students.Get as close to the students as conditions allow.Shift your gaze around the room, making brief eye contact with every person possible.You should be asking questions almost as much as you are making statements, and students need to realize that they are expected to respond to your questions.At the start of the first day of class, I greet the students as I walk in.If they do not immediately greet me in turn, I walk out and walk back in again, repeating the salutation!I greet them at the start of every class, and expect a response.It may surprise you how much this simple thing can “wake a class up.”It is imperative that students realize that you are not a television image, and that they mustinteract with you accordingly.As much as it may torture you, you must give students adequate “wait time” to respond; do not let them think they can outlast you if they are non-responsive.Many times I have asked a question, stood through the silence, then sat down in a chair, propped my feet up, and said, “I’ll wait.”After a few instances of this, they realize that I seriously do need them to be involved and respond.

Overheads and slide shows, a staple of conference presentations, can be death to a lecture if not used sparingly.In fact, I use very few projections in my lectures, and even write on the board very little.This is because I want the students listening to what I am saying, not doing stenography.When I was a teaching assistant, I worked for a professor who routinely projected large amounts of information on a screen.Observing from the back of the classroom, it became clear to me that the students were not listening to a word he was saying.As far as they were concerned, all the important information was on the overhead, and they absolutely had to get it down.He may as well have not been in the room.Projections should be reserved for graphics and animations, and information you will be referencing throughout the lecture, such as data tables.The same should be true of material drawn or written on a board.If students are copying things down, they are usually not listening to you.They are also in danger of just copying symbols, and not being engaged in finding meaning in the words.If they must listen to you, they will likely be more involved.

Although astronomy is a visual science, I rarely have to project images, because the textbook is so full of excellent pictures and diagrams.I require students to bring their books to class every day, mainly so they can follow along with the figures in the book.An image 20 (or more!) feet away from the students on a screen may not be as effective as an image that is literally right under their noses.And the physical act of turning to a certain figure in the text is one more thing to help keep students from disengaging from the class.Who knows, it might even motivate them to read the text!

Probably the most important thing to insert in a lecture is one or more “breaks.”Have the students discuss a concept with a neighbor, or do another activity described below.A well-timed demonstration or presentation of a model can also break up a lecture.The chapters of this Instructor Guidecontain many suggestions for demonstrations and models to illustrate concepts.Of course, the best breaks are the ones that are incorporated into the lecture itself.I sometimes pause to tell students a mythological story about one of the objects under discussion, or to talk about a relevant event or person from the history of astronomy.I also interject personal anecdotes relevant (although often tenuously so) to the matter at hand: stories of my young son, or “glorious tales of my misspent youth” that sometimes set eyes to rolling.You’re not there to be a stand-up comedian, but a little mid-lecture humor can refresh both you and your students.

LECTURE-TUTORIALS

A companion book to the text, Lecture-Tutorials for Introductory Astronomy, 2nd Edition, by Edward E. Prather, Jeffrey P. Adams, Timothy F. Slater, and Gina Brissenden, provides some excellent ways to give students opportunities to teach each other.This is important, because very often the best way to learn something is to try and help someone else understand it.You might want to consider having your students get this workbook, especially if you are teaching a laboratory class, or a course that emphasizes observations over astrophysics.

The procedure I use for the lecture-tutorials is as follows.First, I give the students some background on the subject matter of the activity, usually as part of my normal lecture.Then, I have student divide up into groups of two or three.I usually let them self-select groups, but I do not let them work with the same people over and over.Groups should be no larger than three, and even with three, there is great risk of one member becoming a spectator.I have the groups work through the tutorials, asking them to write or draw on notebook paper to hand in.If a group finishes before the time is up, I encourage them to find another group that has finished, and compare answers with them.After about 30-40 minutes, I have the groups hand in the answer sheets, and we go over the highlights of the activity as a class.You may also want to post answers to the activities where students can read them later.I grade the submitted papers for completeness only, but you may wish to do otherwise.

If you use the lecture-tutorials, it is vital that you include elements of the activities on whatever assessment you will be using.This drives home to the students that the lecture-tutorials are a valuable learning tool, and a good use of their time.It also allows you to see how effective they are, and where there could be room for improvement.

STUDENT RESPONSE SYSTEMS (aka “clickers”)

It is very important to get students involved in the learning process.Recently, methods using student response systems (called “clickers”) have become very popular.There are many ways to use these response systems; the following process is one of the most involved.First, the instructor uses a computer projector to show students a multiple choice question.The subject matter of the question is material that the instructor is getting ready to cover – the technique is rarely used to evaluate, although the system could theoretically be used to give quizzes.Students then “vote” for the answer they think is correct, using remote controls.The remote controls could be bought by the students, or could be the property of the institution.Techniques requiring less technology could involve a simple show of hands, or even the use of lettered or color-coded flashcards, although these methods reduce anonymity.

After results are tabulated, it is possible then for the instructor to compare the results of the vote to the actual right answer.However, the most rigorous application of this technique adds an intermediate step if the voters are wrong or inconclusive: the instructor asks the students to turn to their neighbors and discuss the answer.Such discussion could also be done in small groups.After some discussion, the class votes again, perhaps with results closer to the correct answer.This technique not only allows for valuable interaction with peers, it also allows the instructor to find out what the class knows beforehand.If a class is very knowledgeable about a topic, the instructor can spend less time on the topic.Properly applied, this technique can occasionally save class time!Students also enjoy using the “clickers” and can become more engaged in the class.

Many versions of student response systems are available for purchase.A Web search for “student response systems” should yield many options.Possibly the most challenging aspect of implementing this method is not hardware, however: it’s coming up with good “clicker questions.”The Multiple Choice questions at the end of each chapter in the text can provide some inspiration.Peer Instruction for Astronomy, by Paul J. Green can also help with questions.Pearson Publishing offers two other resources:A DVD titled Interactive Teaching, featuring one the pioneers of teaching with student response systems, Eric Mazur; and Clickers in the Astronomy Classroom by Douglas Duncan.

SMALL GROUP PEER INSTRUCTION

This technique has also been labeled the “jigsaw method.”Students are divided into groups of four or five.Instructor-assigned groups usually work better than self-selected groups, with high-performing students and low-performing students working together.Both types of student will benefit from this; the high-performing students will learn the material more deeply if they are helping their fellows.You may also want to change the groups once or twice during the course, to account for attrition and provide variety.

Give each group a number of questions about the material you are going to cover in the next class, one question for each group member.The “Process of Science” questions interspersed in the text, as well as the “Review and Discussion” questions at the end of each chapter, are excellent models for these kinds of questions.As with the “clicker questions” above, bear in mind the purpose of the technique is not evaluation, although it might be a good idea to include potential exam questions.Between classes, students try to construct an answer for “their question” for the next class.Students meet during class and teach each other the answers to the questions.The instructor can circulate and answer brief questions, but it is important to avoid being too helpful!After students have had time to teach each other, take volunteers to provide answers, and discuss them as a class.