Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: [Phys-l] physics assessment

Never heard of this? Is it a paper, test, book,..?

Forum for Physics Educators <> writes:
What about Jerry Epstein's math assessment?

Joseph J. Bellina, Jr. Ph.D.
Professor of Physics
Saint Mary's College
Notre Dame, IN 46556

On Sep 24, 2009, at 4:22 PM, John Denker wrote:

On 09/24/09 09:10, Anthony Lapinski wrote:

We would like to come up with some sort of "pre-test" to act as a

Good plan!

to give us some sort of indication of which course might be best
for them,
or what "skills" are needed for honors vs regular. We don't want
kids to
be in honors and then feel overwhelmed after the first few weeks.
into another course can mess with their schedules or be impossible
to do.

Right. Putting a student in over his head is a
disservice to the student in question *and* a
disservice to the others in the class, because it
almost-inevitably holds the others back.

The math part of a pre-test is relatively easy. I can test their
algebra/trig skills.


I would test for algebra, geometry, trig, and logic.

Suggestion: The Sam Loyd puzzle books are a bountiful
source of logic questions that don't require much in
the way of specialized knowledge in any field.

Suggestion: Bongard problems are a fun way to test
and/or exercise the logic muscle.

However, most physics problems are word problems, and
these questions are harder to design since the students enrolling
have no formal training in the subject.

1) I'm not sure there is -- or should be -- any "physics"
prerequisite for the introductory physics class. To a
first approximation, I might be content to test for
-- math and logic skills, plus
-- motivation and dedication
and leave it at that.

The motivation check doesn't have to be subtle. I might
1a) How many hours per week are you prepared to spend
doing homework _for this course_? ________

Anybody who answers "zero" is disqualified from the honors
course, either because they have no clue about what is
involved, or they are overcommitted with other after-school
activities ... or because they just aren't interested.
Don't underestimate the value of self-selection. For one
thing, sometimes parents push a kid to sign up for a
course he isn't interested in, and answering "zero" on
the placement test is an honest and convenient way for
the kid to bail out before it's too late.

Also you get to use the answer later, to confront any
student who signed up for the honors course but isn't
doing the homework.

1b) Based on what you know, do you think you would
be better off in:
-- The standard course
-- The honors course
-- The AP course

1c) Why? _____________________

Again, don't underestimate the value of self-selection.

2) To a second approximation, I make a point of not
recognizing any definite boundary between physics and
other fields, including mathematics.

So, I would ask some simple questions that look like
math questions but have a physicsy flavor to them,
such as scaling laws. For example:
2a) Given a solid stack of bricks that is 8 bricks high,
8 bricks wide, and 8 bricks long, where each brick
weighs 6 pounds, how much does the whole stack weigh?
Show your work.

This works better if it is _not_ multiple choice. I
want to see the method of solution. Anybody who writes
it as a one-liner starting with 3 x 2^10 is probably
going to do fine in my course. I value cleverness over
brute force.

All of these questions are designed to work better
_without calculators_.

2b) How much water is there in an olympic-sized swimming
pool? Show your work.
-- 2500 liters
-- 2500 gallons
-- 2500 metric tons
-- 2,500,000 liters
-- 2,500,000 gallons
-- 2,500,000 metric tons

The point here is that you don't need to know the exact
size to find the best answer, because the distractors
are wrong by more than an order of magnitude one way or
the other. Basically I'm testing for courage, i.e. for
not giving up on a problem that requires a little bit
of thinking.

I say "show your work" because I want to know whether
they mis-estimated the starting data (length, width,
depth), or don't know how big a gallon is, or just
bungled the arithmetic.

It is also amusing to see who is freaked out (or not)
by more than one correct answer. This is partly a
check to see who is actually thinking and who merely
has good test-taking skills, i.e. who has been trained
to work multiple-guess questions backwards by checking
each possibility.

Remember that *I* am grading the test, and I'm looking
for more than just quote "the" quote "answer".

2c) Estimate the square root of 50, with accuracy
better than 1%. Show your work.

There isn't much physics in this, but again there
are clever ways and not-so-clever ways of finding
the answer.

2d) We have a small triangle abc and a big triangle
ABC. Each leg of the big triangle is twice as long
as the corresponding leg of the small triangle.
Choose the best answer: Compared to the area of
the small triangle, the area of the big triangle
-- Larger by a factor of 1.4 approximately.
-- Larger by a factor of 2.
-- Larger by a factor of 3.
-- Larger by a factor of 4.

It is always distressing how few get this right, but
when they do get it right, it tells you something.

2e) True or false: A cube has at least one axis of
four-fold rotational symmetry. Explain briefly.

Again, it is distressing how many get this wrong.
They were supposed to have learned this in 3rd grade.

A weakness of this question is that it requires
knowing the terminology, not just seeing the concept.
Perhaps it could be improved by rewording; I don't

2f) True or false: A cube has at least one axis of
three-fold rotational symmetry. Explain briefly.

3) There are also some really simple qualitative physics
questions. For example:
3a) Bricks on a teeter-totter: Three bricks at the
halfway point on one side, versus one brick at full
length on the other side.
-- Does it immediately tip to the left?
-- Does it immediately tip to the right?
-- Or is it more-or-less balanced as is?

4) Last but not least, I would make room for exceptions.
The rule is "passing grade on the placement test, or
instructor's permission". I say this because on many
occasions instructors have allowed me to sign up for
courses where I did not come close to meeting the
prerequisites ... and I have on occasion repaid the
favor by allowing in students who by any objective
measure were verrry underqualified, but who really
wanted to take the course anyway ... and generally
they do fine. Motivation counts for a lot.

Forum for Physics Educators

Forum for Physics Educators