Thursday, August 19, 2010

Transforming Students' "Common-Sense" Beliefs Into Newtonian Thinking

I've sometime been given an argument that such-and-such is correct because ".. it makes sense...", as if the human concept of things that makes sense is perfectly valid. My argument is that "common sense" is nothing more than an accumulation of knowledge. There will be things that won't make sense to someone who hasn't had that particular knowledge.

I was reading this article in Phys. Rev. Special Topics - Physics Ed. Research. In it, the authors were studying the effectiveness of a particular teaching technique - the Just-In-Time teaching - in correcting the students' "common sense" understanding of motion and kinematics mechanics[1]. But what drawn my interest more was the background info that I've been meaning to read, but only until now did I had a chance to actually read (quickly) them, thanks to the references given in this article.

The first paper that I wanted to read was something I've encountered many times already in many of these educational research papers: the Force Concept Inventory[2]. The link should give you an online copy of the paper. But another interesting paper is the one by Halloun and Hestenes titled "Common sense concepts about motion"[3]. Here, they pointed out several erroneous "beliefs" of many incoming college students about basic kinematics.

(a) On the pretest (post-test), 47% (20%) of the students showed, at least once, a belief that under no net force, an object slows down. However, only 1% (0%) maintained that belief across similar tasks.

(b) About 66% (54%) of the students held, at least once, the belief that under a constant force an object moves at constant speed. However, only 2% (1%) held that belief consistently.

(c) About 65% (44%) of the students exhibited, at least once, the belief that an impetus is required to maintain the motion of an object. About 40% (24%) were consistent in that belief. About 37% (15%) maintained, at least once, that the trajectory of an object depends on an impressed impetus, but only 3% (1%) were consistent in this belief. Students with quasi-Newtonian beliefs were far more consistent than the other students.

Strangely enough, some of the students still tried to hang on to their faulty beliefs even when faced with an observation/experiment that clearly contradicted those beliefs.

During the interviews with several of the students, typical classroom demonstrations were given of the physical situations described in a few of the talks on the diagnostic test. The demonstrations appeared to have no more effect on their opinions than mere discussions of the phenomena. As a rule, students held firm to mistaken beliefs even when confronted with phenomena that contradicted those beliefs. When a contradiction was recognized or pointed out, they tended at first not to question their own beliefs, but to argue that the observed instance was governed by some other law or principle and the principle they were using applied to a slightly different case.

Quite an entertaining reading. I would imagine that these things would be something an caring instructor would want to know, i.e. the state of mind of the students in the class, to be an effective instructor.


[1] S.P. Formica et al., Phys. Rev. ST Physics Ed. Research v.6, p.020106 (2010). Papers in this journal are open access, you may obtain a copy of this paper here.
[2] D. Hestenes, et al., Phys. Teach. v.30, p.141 (1992).
[3] A.B. Halloun Am. J. Phys. v.53, p.11 (1985).

1 comment:

Pi-Guy said...

The infamous "Heavy Boots" story that made its way around the Web has occasionally been accused of being an urban myth. That particular story may be apocryphal for all I know; but its essence is alive and well. I speculate that the reason is because there are no important consequences to most people on a personal level for not getting their conceptual ducks all in a row.