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Instructor’s Guide for Light and Matter December 14, 2009 A reform-oriented int

Instructor’s Guide for Light and Matter December 14, 2009 A reform-oriented introductory physics textbook What’s distinctive about this book is that it is reform-oriented: it emphasizes depth over breadth, it is designed to support active learning, and it never intro- duces a new concept with an unmotivated equation. While the reform movement has produced excellent physics textbooks for gen ed students(1) and students majoring in engineering or the physical sciences(2), no such book has been avail- able for the type of course typically taken by life science students: a one-year algebra-based course, or a one-year course with calculus as a corequisite. This book is meant to ﬁll that need. Another unusual feature is that both the book and its supplementary materi- als (in particular, an online answer checker) are designed to support a problem- solving approach focused on symbolic rather than numerical calculation. Com- pared to most books’ homework problems, this one’s concentrate far more heav- ily on problems with symbolic answers. For exampe, a student may be asked to compute a symbolic answer, then check it using the online answer checker, then interpret its meaning, and only then, as a ﬁnal step, plug in numbers and produce a numerical result (which can also be checked online). Basic survival guide Here’s the most vital information you need to know if you’re using the book for the ﬁrst time: (1) I’m committed to making new editions of the books as backward-compatible as possible with old editions (rather than introducing incompatibilities in order to kill oﬀthe used book market). To take advantage of this, always refer to chapter and section numbers in your syllabus, not page numbers. New home- work problems will normally be added at the end, so you can safely refer to homework problems by chapter and problem number. If you have two editions in the same classroom, make sure you’re working from the older edition your- self, so that you won’t be referring to newer discussion questions or homework problems that some of your students don’t have. (2) Don’t be tempted to skip chapter 1 of book 1, since it introduces the students to modes of reasoning involving ratios and proportionalities. If you 1 skip this chapter, they will complain that the homework in the later chapters is impossible. (3) To use the discussion questions successfully, you’ll need to give reading quizzes and explain to the students the need to read the book before coming to class, rather than using the book as a reference, which is what most students are used to doing in science classes. Resources available with this book A complete and up-to-date list of support materials is available at http://www.lightandmatter.com/area1guide.html . If you’re like me, you’re a little cynical about the support materials provided by textbook publishers — most of them are ﬂashy but short on substance. You’ll have to judge my materials for yourself, but I hope you’ll try out the answer checker, called Spotter,(9) if only so that you’ll know your students are using it! Contents 1 Newtonian Physics 0 Introduction and Review 1 Scaling and Order-of-Magnitude Estimates Motion in One Dimension 2 Velocity and Relative Motion 3 Acceleration and Free Fall 4 Force and Motion 5 Analysis of Forces Motion in Three Dimensions 6 Newton’s Laws in Three Dimensions 7 Vectors 8 Vectors and Motion 9 Circular Motion 10 Gravity 2 Conservation Laws 1 Conservation of Energy 2 Simplifying the Energy Zoo 3 Work: The Transfer of Mechanical Energy 4 Conservation of Momentum 5 Conservation of Angular Momentum 2 3 Vibrations and Waves 1 Vibrations 2 Resonance 3 Free Waves 4 Bounded Waves 4 Electricity and Magnetism 1 Electricity and the Atom 2 The Nucleus 3 Circuits, Part 1 4 Circuits, Part 2 5 Fields of Force 6 Electromagnetism 5 Optics 1 The Ray Model of Light 2 Images by Reﬂection, Part I 3 Images by Reﬂection, Part II 4 Refraction and Images 5 Wave Optics 6 The Modern Revolution in Physics 1 Relativity 2 Rules of Randomness 3 Light as a Particle 4 Matter as a Wave 5 The Atom Support for active learning The books provide two main tools for fostering active learning in the classroom: the discussion questions at the end of each section, and the exercises in the back of the book. I spend more than 50% of my class time on these, and have certain methods for using them, but they can be adapted to a variety of teaching styles and methods. In a handful of cases fairly important points are introduced only through a discussion question, not in the main text, so you should make sure at least to skim all the discussion questions to see what’s in them. I sometimes do the discussion questions as a dialog between me and the class, and sometimes have the students form small groups. The former technique often allows for a higher level of discussion; in the latter approach one must be very careful to make the level of the questions easy enough so even the weakest groups will not be demoralized. The small-group method works best with small classes. 3 I have found that there are three keys to using active learning successfully in the classroom: (1) One must explain to the students the reason why they should read the book before coming to class. Unless it is explained to them precisely why this is crucial to the active learning techniques they will be participating in, they will treat the book as a reference only, as is the universal custom among students in traditional courses despite all the usual admonitions to contrary. Reading quizzes are absolutely necessary as well. (2) Always start with discussion questions that seem ridiculously easy, and then move on to more diﬃcult ones as seems appropriate. It is not hard to judge the relative diﬃculty of the questions in advance, but the absolute level can be harder to determine. Often the questions that seem insultingly simple are surprisingly diﬃcult. Nothing is lost by starting with easy questions, and it builds the students’ conﬁdence. (3) It is vitally important to provide some clear method of feedback so that incorrect ideas are detected quickly and the whole class ends up understanding the concept correctly. This happens naturally if you do the questions as a dialog between you and the students, but if they are working in small groups you will need to provide some mechanism. When my students are doing small group work, I encourage them to write down their answers, so that I can look over their shoulders and see what they’re thinking. It can also be helpful to ask a particular student to repeat her explanation to the whole class. Getting psyched Attention to some psychological and social factors can also help to make the method more successful. Experience (refs (7) and (8), and my own anecdotal evidence) seems to show that it is poison for active learning if one grades on a curve in the full sense of the word, so that a certain percentage of students is guaranteed to fail and no more than a certain percentage can get A’s and B’s. Classic grading on a curve has the eﬀect of setting the students against one another, which is antithetical to the cooperative nature of the active learning activities. This does not mean that one must use the traditional scale on which 90% is an A, 80% is a B, etc., but it does mean that the standards should be absolute rather than relative. Book 1: Newtonian Physics Terminology and order of topics The order of topics is a little diﬀerent than in most books. In keeping with the philosophy that no deﬁnition should be given without physical motivation, dynamics and kinematics are introduced in parallel rather than one after the other. The kilogram and the newton are introduced before any formal discussion of dynamics. The chapter on velocity includes a discussion of the center of mass 4 and the principle of inertia. The chapter on acceleration introduces free fall and recaps Galileo’s dynamical argument to explain why heavier bodies fall the same way as light ones. One-dimensional kinematics and dynamics are developed before generaliz- ing to three dimensions. However, some simple and intuitive ideas about force vectors are introduced early on so that one can deal with one-dimensional mo- tion in which there are some forces perpendicular to the line of motion which nevertheless cancel out. Vector components are introduced in a chapter by themselves, before the chapter on vectors. During the period between these chapters, one must refer to “the x component of the acceleration,” for example, rather than “the x component of the acceleration vector.” A little of the standard kinematical terminology is eliminated in order to make it seem less like the initial material on kinematics is just a matter of memorizing a long list of confusing deﬁnitions. ‘Speed’ is introduced only in a discussion question, and is not used elsewhere in the book without explanation. ‘Average velocity’ uploads/Philosophie/ guide - 2023-05-29T152848.171.pdf