Monday, September 3, 2012

WHAT was that Harvard Twit Thinking?

I am writing of course concerning assistant professor Matthew Platt’s Introduction to Congress class in the spring currently under investigation for cheating. This was the end of the previous academic calendar year, the final semester, so now apparently a number of students are hung out to dry in a possibly cheating mess when their grades had already been finalized, and a number have already graduated and find themselves in new jobs. In one case, a former student graduated cum laude and is now wondering what he's going to tell his new boss.

Evidentlly, dozens of Harvard students are in similar positions after Thursday’s announcement that about 125 of them — almost half of the 279-student “Intro to Congress” class — are suspected of cheating on the course’s final exam. This is based on a TA (they refer to them as "teaching fellows" at Hah-vahd) having noticed "suspicious similarities among many of the test answers and notified the professor."

Other faculty members have weighed in and said they believe take-home exams entail too much temptation. On blogs and in interviews Friday, Harvard professors raised a cry: bring back the in-class final.

Well, DUH!

Why would ANY university of any repute countenance such nonsense – especially for an essentially descriptive course- in the first place? (I will get to why not all take home tests need be banned, as I shown an example of one of my own from Calculus Physics).

My own conjecture, unlike some professors - e.g. Howard Gardner, quoted in The Boston Globe, isn't based on "loose ethics" or a tendency to take "short cuts" but rather the total culture of academic deterioration that's set in since universities turned courses and electives into exercises in consumption. This is typified in the end of term baloney known as "teacher evaluations" when most of these kids - even at glorious Harvard- aren't equipped or mature enough to objectively evaluate dog poop. (They tend to view any prof that dares award them less than what they expect as "unqualified" or a "poor teacher" or some other rot)

These evaluations, which I personally believe have been a prime factor in ever diminishing academic quality, have led to a "race to the bottom" by virtue of profs trying to outdo each other to see who can award the most high grades. (A's being preferred, of course). The more high grades, the more popular the course, and the more kids enrolled translates to a higher dept. profile and likely financial support - or at least a reduced threat of cuts!) Indeed, the Harvard prof in question, according to one innominate student quoted from an email appearing in a piece, evidently bragged that he “gave out 120+ A’s last year” and would do the same this year".

If true, and again this is only the student's claim in an email, this would be grade inflation run amuck but more or less understandable in an environment where students myopically measure teaching quality by the grades they receive. (Omitting the component of their own earnest effort)

Also, this has been deplored for years by many of us who value content quality and actually demanding students earn their As, rather than getting them gratis to appease them. A case in point is a Harpers magazine article from September, 1997, p. 39. The author lays out his students consumer mindset approach to teacher evaluation in clear, stark terms:

"They're pitched into high writing gear....stoked on a procedure they have now supremely mastered. They're playing the informed consumer, letting the provider know where he's come through and where he's not up to snuff. "

The "provider" being the university administration or the Chairman of the Department, who is informed that any guy that has the temerity to dole out Ds or even Cs has come up "short" and doesn't belong there!

Now, should all take-home tests be banned? Not necessarily! I would say only in descriptive courses, as in history, economics, government, or any similar disciplines. In physics, however, I have from time to time allowed take home finals such as the one below, with a strict 1-day (night) time limit and no sharing. The latter is not difficult to check since each student has his-her own say of problem solving and if a 'homogenous' form is manifest on the exam they know they all flunk:


Take Home Exam: Calculus Physics I FINAL: You have ONE DAY to complete the following – NO cooperative working or sharing! DO ALL FOUR Problems.

1)Find the root mean square velocity of a molecule of hydrogen at a temperature of -20 C on Mars’ equator if the atmospheric pressure is 0.0056 bar. (Earth’s is 1.0 bar). Take the molecular weight of hydrogen as 2.016 g/mol.

b) A group of 4 astronauts lands on Mars with solar radiation collection material of total area 2000 m^2. If the efficiency of the material is 30%, and the ambient night time temperature on Mars (for their base location at Isidis Planitia) is -40 C (10C day time), will they have adequate collecting material if the solar constant on Mars is 620 W/m^2? (Assume insulating material with a thermal conductivity of 0.08 W/mC, and a need to keep the inside area of their domecile at least at 10 C, requiring solar radiant energy collected of at least 1,200 W per minute for an area of 10 m x 10 m.)

c) Estimate the thickness of insulating material they're likely to need in order to make it work. Comment on whether this expedition is even feasible given the limits of their materials, and that no more than 100 m^3 of insulating material can be taken.

2) Examine the pendulum system shown in the diagram (Fig. 1). Here, h2 = 1.7 m and h1 = 1.0 m. Given a pendulum length, L, write out the Lagrangian for the system, i.e. difference between its kinetic and potential energy, using: g, L, h2, h1 and the deflection angle Θ.

b) Hence or otherwise compare the velocities of the pendulum bob of mass m (= 0.1 kg) for the same values of h2, h1 if an experiment in evaluating energy change is conducted on both Mars and Earth at the same time, for the same deflection angle Θ and length, L = 1.0 m. (Take the acceleration of gravity on Earth as 9.8 N/kg,and on Mars as 3.7 N/kg) Compare also the potential energy in each case. Why or why not would these be different? (Take the deflection angle to be 15 degrees in each experiment.)

3) In the diagram shown above, a slab of silver with dimensions: z1 = 2 cm, y1 = 1mm, carrying 200 A of current in the +x^ direction. The uniform B-field has a magnitude of 1.5 Tesla. If there are 7.4 x 10^28 free electrons per cubic meter. Find: a)The electron drift velocity b)The magnitude and direction of the E-field due to the Hall Effectc)The magnitude of the Hall EMF.

Now, change the directions in the diagram, so the thickness (y1) is now in the x-direction, and the current I is now flowing in the +y-direction, and B is in the (–x)-direction. Let dimension z1 be half the size that it was previously.

If there are now 7.4 x 10 ^27 free electrons per cubic meter. Find: a)The electron drift velocity b)The magnitude and direction of the E-field due to the Hall Effect, c)The magnitude of the Hall EMF.

4) In some solar flare models, the emergence of the flare is modeled after inductive sparking at switch contacts, with solar loops taking the place of inductive coils. The estimated current in these loops is about 10^11 A. If in one such set of loops the associated inductance L is observed to decrease from 5.6 H to 4.3 H in 15s, then estimate the power released in the flare based on this simple model. What total flare energy is released?

Extra Credit (10 marks): The Hall electric field (E_H) for a sunspot has been defined by (Bray and Loughhead, Sunspots, 1964):

E_H = 1/nec [j x B/u_o]

Where j is the current density and u_o is the magnetic permeability of free space. Draw a sketch of such a sunspot showing how a Hall (circuital) current (I_ z )would arise from the cross product V(r) x H_z (= B_ z / u_o) where V(r) denotes a radially- directed (outward) velocity in the spot.(Hint: Use the right hand rule to give separate directions for H_z , I _z , and V(r) )


Bottom line? The error of the Harvard prof was in allowing a take home exam for a subject that ought not merit such, because of its essential descriptive nature. By contrast, any quantitative subject such as: calculus physics, astrophysics, mechanics, thermodynamics, differential calculus, or advanced calculus (complex analysis) is fair game, at least on occasion and provided a suitable time frame is given.

'Nuff said!

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