Contents: Teaching Physics in 21 st Century. What has changed? What has changed? 20/6/2013. sharing of experience. T.K. Ng (HKUST)

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1 Contents: Teaching Physics in 1 st Century sharing of experience T.K. Ng (HKUST) 1. Background: What has changed compared with 10, 0 years ago? New Education system in HK, New students profile Different Learning Philosophy New horizon in Physics. What are we doing in response? New modes of teaching, new style of assessment Role of mathematics Use of Internet/multi-media resources education system education system School-Based admission versus Program admission Whole person development is emphasized Students have to acquire diverse background of knowledge Students have to have the ability to upgrade themselves even after graduation (whole-life learning) Problem: We (both secondary school & university) are teaching physics to students with very diverse background! For example: at HKUST All students have to talk 1 calculus course All students have to talk courses in science & technology, humanities and social analysis (Common Core) All Engineering students have to take 1 physics course All Science students have to take 1 course from each science discipline (Phy., Chem., Bio) Problem: We (both secondary school & university) are teaching physics to students with very diverse background! 1

2 Different philosophy of learning The philosophy of both learning at working has changed Whole person development is emphasized Communication/language and other general skills are emphasized Rigorous scientific (quantitative) approach/skill is for small number of students only But yet students are supposed have a broad knowledge base and are able to pick up the basic ideas behind ALL fields! Problem: We (both secondary school & university) are teaching physics to students with very diverse background! New Horizon in Physics The field of physics has evolved drastically in the past 30 years Idea of particles and Newtonian mechanics is NO-LONGER fundamental in our modern application of physics Fields (EM field, magnetic field, etc.) and Quantum Physics is fundamental to our modern technology In string theory we are talking about whether we can design a new universe with different fundamental laws of physics Yet: We need to teach the physics fundamentals (mechanics, E&M, Thermodynamics ) to understand new developments in physics (fundamental physics is like calculus ) (Field) (Thermal) New challenge in Physics The problem of students not having enough background in Mathematics before taking physics is just one of the many problems under the big picture of the changing world of education! What can we do? The goals of teaching has to be defined separately for different groups of students Different ways of teaching for different kinds of students different ways of assessments correspondingly! (In HKUST we have different calculus/physics classes designed for students with different academic background. UST example: 1 st Yr. Physics courses Common Core and School-Sponsored course (Energy, Astronomy, Relativity) Requirement for students with zero background in Physics (Eng. & Sci.) (General Physics 0) Requirement for non-major students (General Physics Ia) Requirement for major students (General Physics Ib) (In HKUST we have different calculus/physics classes designed for students with different academic background. We have also ordinary and honored courses for majors ( nd and above years)

3 New ways of teaching - Share of experience A large number of students have interests in the concept and/or application of physics but not the mathematical details of the theory - Examples to share: harmonic oscillator, relativity, Galilean invariance (application in daily life) Key idea: Teach physics concept without using mathematics but try to explain/demonstrate a physical picture using whatever means. Mathematics come in only if you want to have quantitative answers/numbers. Notice: students learning concept this way answer questions in examinations differently Example 1: Galilean invariance 1. The laws of physics is insensitive to uniform motion (or Newton s Law is the same in all inertial frames.) [ Recall Newton s First Law: An object remains in its state of rest or uniform motion (moving with uniform velocity) in a straight line if there is no net force acting on it. ] The important of Galilean invariance can be seen from the following example: Imagine you are travelling on a very big boat Maybe in this one This is a very big boat, and is very stable so that you do not feel any floating up-and-down motion of the boat. Suppose you are living at the interior of the boat and have no window to look outside. 3

4 One day, you wake up from a nap, and out of curiosity you want to find out whether the boat is Expt.? actually parking somewhere, or is traveling with a uniform speed. Can you find that out without asking someone, and without going outside? What Galilean invariance said is that you cannot determine whether you are moving (with uniform speed) or not if you perform experiments involving Newton s Law inside the boat, like looking at the trajectory of a little ball that you throw up, or looking at the motion of anything you see.? equator:? 1600km/hour 3km/sec Why don t we feel that? 4

5 Question in exam: Two space ships are traveling in parallel in this universe with same velocity v (see figure) separated by distance. The two ships are communicating with each other either by sending light signal or by sending boxes of papers in between. v v d Example : Projectile motion - Use of internet resources to make class more interesting Students got bored by always facing a single teacher in general they think that videos are more interesting. They learn English They will find out that you are actually teaching very well Video 1 I)Let the velocity of light be c, how long does it take for the light signal to go from one ship to the other? Explain your answer. II)Let the velocity of the traveling box be u (relative to the ship), how long does it take for the box to go from one ship to the other? Explain your answer. Video Example : Projectile motion Example 3: complicated/unfamiliar functions -Exercise: What is the longest (horizontal) distance a projectile can go if it starts with v 0 =10m/s Ans: v0 d max ~ 10m g 1 0 v0 sin t gt ; d v cos t v0 ( sin cos ) v0 sin d g g 0 - Harmonic (sin t, cos t) functions Solution of harmonic oscillator We don t prove that it s the solution of Newton Law for harmonic oscillator in our class We show that wave motion is useful and realistic and can be understood from harmonic oscillator-like equations Mathematics is used to write down a answer we know is correct (animation) (wave in water droplet) Unit is important for the student to have A good feeling of what is physically happening You don t need calculus to get the answer if you understand what a sin function is! Exercise: what is roughly the frequency of oscillation, in the demonstrations? 5

6 Example 4: Relativity - Use of internet resources to explain difficult concepts and to connect what you are teaching with the most fascinating development in physics in the world I start with a story.. Videos are good for explaining difficult concepts I show more than 10 different videos to explain relativity Examinations are concept driven, no derivation, simple application of equation, explanations needed. Mathematics is used to write down the answer we know is correct ~ Thank you ~ lec Video 3 Video 4 Video 5 6