A common difficulty for introductory physics/engineering students arises from the fact that concepts such as force and mass have a variety of colloquial meanings as well as the precise meanings ascribed to them in classical physics. The differences in meaning are related to the development of so-called "naïve" concepts of force, weight, and mass. It is often difficult for an instructor to anticipate at what point or in what ways these naïve concepts (or other "misconceptions") may be obstructing a student's grasp of the material. The method described here of "Weekly Reports," as developed by Professor Eugenia Etkina of Rutgers, provides an instructor with immediate feedback to three questions:
The reports were graded and had the same weight in points
as all other homework exercises. Extra class points were given
for interesting questions. Each week a list was made of the most
difficult/interesting questions and the last recitation section
of the week was devoted to discussing the questions via a group
method a la Eric Mazur. The course grade was based on a "point-accumulation"
system (i.e., all students with point totals in a given pre-defined
range received the same grade). The method was tried in the summer
of 1977 at Rutgers University in an introductory physics course,
"Extended General Physics," designed for at-risk students
in biology and pre-med majors with physics requirement. The class
had 16 students.
The over-arching goal of the method is to: provide immediate feedback
from the students; to see whether the students have a coherent
picture of the material; to answer their questions consistently;
to identify typical misconceptions and mistakes, to match the
levels of difficulty of teaching and assessment.
As the course progressed Professor Etkina asked the students to
mention the specific homework exercises that related to their
responses to questions 1. and 2. above, so that responses took
the forms: "I learned the concept of average velocity; problems
4 and 6 from the homework are based on this concept." or
"I did not understand how to graph speed vs. time; that is
why I think I could not do problems 7 and 8."
The method has been so successful that Professor Etkina now uses
it in every course she teaches.
Analysis of Question 1.--What did you learn?
Analysis of the reports indicated that what the professor
wanted the students to learn and what they thought they had learned
matched by approximately 90%. However, the sophistication with
students approached this question varied substantially from student
to student. For example, some students simply listed facts and
laws, "I learned the difference between a vector and a scalar.";
others listed skills, "I learned how to draw free-body diagrams.";
very few could express what they had learned conceptually, e.g.,
"Always derive a formula for the net force using a free-body
diagram."
More importantly, the level of sophistication progressed as the
course progressed. For example, in the beginning one student wrote,
"I learned that vectors are magnitude with direction using
arrows to show vector direction", and "Can't say something
moves unless it is with respect to something." In week 5
the same student wrote, "For wave propagation we need a vibrating
source, and a medium in which particles interact with each other.
The difference between wave motion and the other kinds of motion
we learned before is that in wave motion only energy propagates
not substance."
Analysis of Question 2. --What remains unclear?
Of the total of 254 responses as to what questions remained unclear 66 responses were simply of the nature "I didn't understand how to do problem 55 in the homework." However, sometimes the responses could be used for a later class topic, e.g., "Is gravitational potential energy the only kind of potential energy or there are others? If yes, what is responsible for them?" In fact, elastic potential energy, interference and standing waves were all introduced in response to questions asked in the weekly reports. Some questions were quite sophisticated, "In wave motion we can find three different velocities: the velocity that shows how fast displacement changes, the velocity that depends on the medium, and the velocity that is the product of wavelength and frequency. How do these different velocities relate to each other? Which one depends on which and why?"
A number of students used this section of the weekly report to
give feedback as to how they felt about that weeks level of difficulty
e.g., "I did not feel confident doing my homework this week."
This opened lines of communication between the professor and students
that positively affected the atmosphere of the entire class.
Analysis of Question 3.--What would I ask if I were the professor?
Students listed a total of 200 conceptual questions, and both
qualitative and quantitative problems. This covered approximately
65% of the material that had been planned for examinations. After
the first week, some student responses suggested novel examination
procedures, e.g., "To test your students regarding their
knowledge of the material in week 1, you could perhaps ask students
to tell you in writing all they know about a certain topic in
the material that we learned. Along with a question from each
topic, you could also ask a problem related to that topic."
Upon being prompted for more specific responses students tended
to simply list the homework problems that they considered the
most important. Gradually, with more prompting they offered more
reasonable exam questions.
Many questions indicated a desire to relate the phenomenon they
studied to their own lives, e.g., "What are everyday examples
of the Doppler effect." Two of the stronger students provided
questions that were actually used on a weekly basis for quizzes,
e.g., "(1) Why does the Earth do no work on the Moon? (2)
A pilot travels all over the world and lands at the same place
where he took off from. Will the work done by the net force be
positive? Negative? Zero? Explain. (3) How do you find the work
done by a force that is not constant? Explain."
The questions generated by student responses to questions 2. and
3. above were divided into four groups indicating the level of
difficulty. Questions that asked for factual information were
assigned to the "minimal level" (for example "What
is a physical pendulum?"). Questions that asked for comparative
information were described as "low level" (for example
"What is the difference between a simple pendulum and a physical
pendulum?"). Conceptual questions and questions about different
procedures done in previous classes were to be considered at a
"moderate level" (for example, "How can we prove
that the period of a simple pendulum does not depend on its amplitude?").
The "highest level" was assigned to questions that required
explanations not given in class before and that usually start
with "Why?" (for example, "Why is it that only
a force that is linearly proportional to the displacement can
provide a system with simple harmonic motion?"). The resulting
distributions are presented in the chart below. Note how students
are more likely to ask the higher difficulty questions to clear
up their own confusion in comparison to what they would like to
see on an exam.
Professor Eugenia Etkina
Rutgers, The State University of New Jersey, Graduate School of Education
email: etkina@rci.rutgers.edu
phone: (732) 932-7496 ext. 339
mailing address:
Professor Eugenia Etkina
Rutgers- State University of New Jersey
10 Seminary Place, New Brunswick, NJ 08901-1183
Those interested in further information regarding this method may contact professor Etkina at the addresses above.
