JOURNAL OF RESEARCH IN SCIENCE TEACHING VOL. 28, NO. 1, PP. 3-18 (1991)

TEACHER AWARENESS OF STUDENT ALTERNATE CONCEPTIONS ABOUT ROTATIONAL MOTION AND GRAVITY

TERRANCE BERG AND WYTZE BROUWER"

Department of Secondary Education, University of Alberta, Edmonton T6G 2G5, Canada

Abstract

Twenty high school physics teachers were interviewed to determine their awareness of student alternate conceptions in the areas of force and gravity. The teachers were also asked to indicate preferred teaching strategies dealing with alternate conceptions. Teacher predictions of student responses were compared to alternate conceptions held by 315 grade-nine students and published findings from other research studies. Edmonton students were found to possess nearly every alternate conception identified in previous research, in similar proportions. A few previously undocumented alternate conceptions were also identified. At times, students were observed to arrive at the currently acceptable conclusion by using alternate conceptions. The high school physics teachers, as a group, identified nearly all the alternate conceptions used by the students. However, individual teachers were generally aware of only a few alternate conceptions, with fully one third of them possessing alternate conceptions themselves in one or more of the tasks. The teachers were also unable to predict with any accuracy the different types of student responses or the proportion of students choosing each alternative. The teaching strategies outlined by the teachers would be considered only partially effective according to current research findings.

Introduction

In recent years, a great deal of attention has been paid to student alternate conceptions of scientific phenomena. These alternate conceptions have been described by different researchers as misconceptions, preconceptions, alternate frameworks, and children's science (Gilbert & Watts, 1983). The results from various studies have shown that students have concepts of the natural world that are quite different from those of scientists. Since science education has been structured around the scientists' concepts, the implications of such findings could prove to be revolutionary. The tabula rasa conception of the learner has come to be replaced with a concept of a learner who brings to class a complicated body of personal knowledge and understanding (Ausubel, 1968; Pope & Gilbert, 1983; Driver, 1981; Erickson, 1979; Osbome & Gilbert, 1980).

The teacher must, therefore, be aware of student alternate conceptions of natural phenomena and how students can even gain incorrect conceptions from instruction

* Joint appointment in Department of Physics

0 1991 by the National Association for Research in Science Teaching Published by John Wiley & Sons, Inc. CCC 0022-4308/91/01 OO03-16$04.00

4 BERG AND BROUWER

(Watts, 1983; Stepans, Beiswenger & Dyche, 1970; Hashweh, 1988). Examples used to illustrate a concept during instruction may convey a totally different meaning to the student, leading the actual outcome to be different from the intended (Anderson, 1986). For instance, a common student misconception that gravity exists only inside a planetary atmosphere (Gunstone & White, 198 1; Watts, 1982) could dramatically affect student understanding of the apparent weightlessness of objects in an earth orbit, or of astronauts standing on a body not massive enough to hold an atmosphere.

More recently, researchers have tried to construct instructional activities designed to eliminate false conceptions and prevent future misconceptions (Minstrell, 1982; Hart, 1987; Shuell, 1987). Researchers have studied populations from child to adult and from student to teacher (Arons, 1981; Champagne, Gunstone & Klopfer, 1983). Alternate conceptions have been found in all age groups and have proved to be very resistant to change. Often, misconceptions held by older people are just sophisticated versions of the earlier alternate conceptions (Stepans, Beiswenger & Dyche, 1970; Clough, Driver & Wood-Robinson, 1987). However, little research seems to be available dealing with teacher awareness of student alternate conceptions, in spite of the fact that teachers’ awareness (and subsequent usage) of this information is an important purpose of the research.

Watts and Zylbersztajn (1981), for example, found that, while the British science teachers studied were generally aware of student alternate conceptions in the area of force and motion, and action-reaction forces, these teachers were “not very good” at predicting student-held conceptions on the relationship between weight and height, or the concepts of force and gravity. Osborne, Bell, and Gilbert (1983) also found that secondary school teachers were “largely unaware of children’s science and are frequently not sensitive to the viewpoints children bring with them to science lessons.” Anderson and Smith (1985) reached similar conclusions in the case of grade-five science teachers.

The purpose of this study was to explore teacher awareness of students’ alternate conceptions and teaching strategies used to instruct these conceptual areas. Specifically, this study attempts to investigate the following research question:

1. Do entry-level high school students in Edmonton, Alberta, Canada hold the same alternate conceptions that have been identified in previous research in the areas of force and gravity? Are high school physics teachers aware of student alternate conceptions in the areas of force and gravity? Do high school physics teachers have teaching strategies to deal with student alternate conceptions (in the areas of force and gravity) that would be considered effective according to current research? If so, what are their teaching strategies?

2.

3.

Studies show that large numbers of students hold alternate conceptions and these must certainly impair the students’ ability to learn physics. Research into teacher awareness of student alternate conceptions and the preferred teaching strategies may provide some explanation for the large numbers of students who consider physics difficult to comprehend.

In conducting this study, its scope was arbitrarily narrowed to physics teachers and students from the city of Edmonton, Alberta. Specifically, this study involved 20 high school physics teachers (from public, Catholic, and private schools) and 315 end- of-grade-nine junior high school students from feeder schools to the high schools

STUDENT ALTERNATE CONCEPTIONS 5

employing the above teachers. These students were nearing the end of a three-year sequence of science courses including life science (grade seven), earth and space science (grade eight) and physical science (grade nine). The principals of the schools were contacted and, with one exception, allowed their grade-nine students to participate in the study.

The teachers were queried only about their perceptions of student alternate conceptions concerning force and gravity, as these conceptual areas were among the earliest to be studied and thus assumed to be most familiar to the students and teachers. The teachers were asked to limit their predictions to just those students who were entering physics 10 (approximate ages 14-15 years). The tasks were drawn from a variety of sources (McCloskey, Carmazza & Green, 1980; Osborne, 1982; Lambert, 1981; Watts & Zylbersztajn, 198 1) to compare Edmonton grade-nine student predictions with an international population. The existence of the international results also allowed us to assess with more confidence the deviation of teacher predictions or expectations from the actual student performance on the tasks.

The Student Task

The first question (Figure 1) was drawn from a study originally carried out at Johns Hopkins University (McCloskey, Carmazza & Green, 1980). In this question students were shown the top view of a ball being rotated in a circle, at the end of a string. The students were told that the string broke at a certain point and were asked to draw in the path they expected the ball to travel. In addition, students were asked to give a reason for their choice of path.

Table I summarizes both the student responses to the question posed and the grade- ten physics teachers' predictions of the percentage of students choosing the various responses. It is clear from Table I that the physics teachers drastically overestimated the number of students choosing the correct response (tangential motion) and under- estimated the number of students who predicted that the ball would continue, at least initially, to follow a curved path.

From the written responses the most commonly held student conception was that a circular force (or impetus) could be given to an object, forcing it to continue to

Fig. 1 . Figure of a metal ball rotating at the end of a string above the head of the observer. Students were asked to predict the path the ball would break after the string broke at point A.

6 BERG AND BROUWER

TABLE 1 Comparison of Physics Teachers’ Expectations of Question 1 to Grade Nine Edmonton

Students and Johns Hopkins University Students.

Job ii s Ho p k i ns S t ud 1’nc 5 P h y s i c s

S t uden t s t o Take E x p r r t d t ions

Ed m o n t o 11 Ed m o i l t on

Student Response Un i ve r s i t y P la nn 1 ng Teachers

P h y s i c s

Tangent ia l 501 18.67 3 5 . 6 %

Continues in a curve 28:; 5 3 . 6 L 1 9 . 5 7

Angled outward bX 1 3 . 7 2 9 .4 r

Radia l ly outward 6% 3.8% 29.n”

Other r e s p o n s e s 10% 10.&7 6 .57

T o t a l r e s p o n s e s ( N = 50) ( N = 1 8 3 ) ( Y = r n )

follow a curved path. Surprisingly, only 3 of the 20 physics teachers identified this alternate conception. The most common student alternate conception expected by the teachers was that of a “tug of war” in which students predicted that a “centrifugal force” would compel the ball to fly outward (radially) once the string was broken. Only a small percentage of students actually held that preconception.

Another common student conception was that the string exerted a tangential force on the ball and hence would cause the ball to fly out tangentially once the string broke. This alternative conception of a force always acting in the direction of the motion reappears several times in the other tasks.

The second question (Figure 2 ) , drawn from Osborne (1982), shows a t. inis ball being thrown up in the air. Students were asked to identify the total force acting on the ball on the way up, at the top, and on the way back down.

No Force K’ i f Fig. 2. The total force on a ball while it is rising, at the top of its path, and while it is falling.

STUDENT ALTERNATE CONCEPTIONS 7

TABLE I1

Edmonton Osborne Edmonton Grade (1982) P h y s i c s

S tudent Kes j l t l l l 5 t ’ Uine S t u d e n t s T e a c h e r s Stud en t s 1 5 y e a r s E x p e c t a t i o n s

of Age

On ;Jay l ‘p . . . Force Up A t The Top . . . No Force On Way D o w n . . . Force D u w n

On Way L‘p ... Furce Oown A t The T o p . .. No Force On IJJY Down . . . Force Llp

On Nay Vp ... Force Up A t The Top . .. Force D o w n On Way Down . . . Force D o w n

On gay Up ... Force Down At. The Top . .. Force D o w n On Wdy i h w n . .. Force D o w i ~

On Way Up ... Force D o w n .At The Top . .. No Force On Way Down ... Force D o w n

0 t her Re s p o n s r s

Tot 1 Responses

56 .2% 66.1% 32.5%

9.8%

8 . 9 %

6.7%

4.1x

1 4 . 3 % 4 .Q% 31.7%

( Y = 315) ( N = 1 7 4 ) ( N = 2 0 )

9.8%

9 . 2 %

0.8%

16 .7%

5.7%

5 . 2 %

11.5%

6.8%

As indicated in Table 11, the Edmonton students showed little difference in their responses when compared to their counterparts of approximately the same age in the Osbome (1982) study. However, the teacher predictions of student responses differ significantly in a number of ways from the student responses. First of all, the teachers underestimated the fraction of students who inferred that the force is always in the direction of the motion and were almost totally unaware of the student conception that the total force is in the opposite direction to the motion. Another popular student conception was that a “force” (or impetus) can be given to the ball. This force is slowly overcome by gravity which begins to dominate at the top or when the ball has started to descend. This impetus conception led some students to choose the first response in Table 11, and others to the third response.

The teachers also expected that nearly 12% of the students would correctly respond that the gravitational force would act downward in all three situations. The actual percentage of correct student responses (6%) agrees well with the results from Osbome’s (1982) study.

Our grade-nine students also demonstrated difficulty in understanding the situation of the ball at the top of its path. The students appear to echo Simplicio’s difficulty in understanding how a rising body “can continue to move without limit always at a slower rate” and yet come to a stop at the top of its path (Galileo, 1638, p. 164). The prospective physics students held at least three conceptions concerning the situation of the ball at the top of its path:

8 BERG AND BROUWER

I .

2.

The ball comes to a stop for a finite length of time. In such a case, of course, no force would be expected to act on the ball while it was stationary. The ball comes to an instantaneous stop at the top. While this is the currently accepted conception, it still led students, in most cases, to predict that no force would be acting. The object does not stop, but merely changes direction. 3.

Nineteen of the 20 teachers indicated awareness of the student conception that the force must always be in the direction of the motion, but underestimated the prevalence of this conception. Also, six of the 20 teachers believed this to be the currently accepted conception! Five of the 20 teachers showed awareness of the impetus conception, but no teacher appeared to be aware of the possible student conception that the force would act in a direction opposite to the motion of the ball.

Ten of the 20 teachers predicted that a significant number of students would hold the alternate conception of “no visible contact, no force.” While this was, historically, a serious point of contention between Newton and his European critics (Hesse, 1965), not a one of the 315 students referred to this alternative conception.

The third question (see Figure 3 ) , drawn from Lambert (1981) and posed a situation in which an astronaut was making repairs on a spaceship in a polar orbit around the earth. While above the equator, the astronaut let go of the spaceship. Students were asked to predict and then draw where the astronaut would be when the spaceship was above the North Pole. Table Ill shows the student responses in Lambert’s study, our students’ predictions, and the physics teachers’ predictions of how their prospective students would answer the question.

This spaceship question and the following moon gravity question were the only ones in which there was a large difference in responses between grade-nine students planning to take physics and those not planning to take physics in high school. Whereas the percentage of grade-nine students choosing the “correct response” is very close to that found by Lambert (1981), the percentage of prospective physics students who

Fig. 3 . The eventual position of the astronaut who lets go of the spaceship.

STUDENT ALTERNATE CONCEPTIONS 9

TABLE I11

S t r l d r n t Rcs Ipo nsc Lambe r t Edmonton A l l G r a d e E d m o n t o n S t lldy G r a d e N i n e Nine P h y s i c s ( 1 9 8 1 ) S t u d e n t s S c i e n c e T e a c h e r s Grade T e n P l a n n i n g S t u d e n t s Expectat ions P h y s i c s to t a k e S t u d e n t s P h y s i c s

S t . r y s w i t h S p c e c r a F t 2 7 . 5 2 37 .7% 2 9 . 2 % 3 8 . 5 %

Fd11.i l i e h i n d i n Orbit E 2 . 5 X 7 . 7 2 8.6% 9 . 5 %

K t m q i n s a t ICqudtur 3 2 . 5 2 18.6% 18.1% 2 9 . 3 %

F.1115 Towdrd E d r t h 1 I). ox 4 . 9 % 6.6% 1 1 . 7 %

I l r i f t s 0uLw:irds from 5 .0% 1 1 . 4 x 12 .4% 7.8% t i i t ' L i r t h

Otl i t~r K L x s p < ) i l s c J s 2.5x 1 9 . 7 % 2 5 . 1 % 3.2%

' I ' l l t , I 1 l < , ~ s p ~ l l S ~ ~ s ( S = itl) ( N = 183) ( N = 3 1 5 ) ( N = 2 0 )

chose the correct response is very close to what their future physics teachers predicted it would be. However, the physics teachers incorrectly identified the most common student justification for the correct response. The majority of students choosing the correct response did so because they believed that both the astronaut and the space ship were moving freely in a circular orbit-under the action of no force. A typical student response was as follows:

He moves with the ship because there is no gravity and no force in space. So when something moves one way it stays going that way . . .

None of the teachers showed awareness of the prevalence of this natural motion conception among their students. Here also Galileo's discussion (Galileo, 1638, p. 166) shows how common this conception was in medieval times and earlier. A minority of the students choosing the correct answer did so because they believed correctly that the force of gravity would cause both the astronaut and the spaceship to continue to move in the same orbit.

More than half of all students expressed a conception that there was no gravity in space and used it to justify a variety of answers. For example:

He will be in the same place because there is no force moving him forward as there is to move the spaceship forward.

The movement of the ship keeps it in orbit but the astronaut has no propulsion, so he would fall to the earth because of the earth's gravity.

Although the ship can push itself along to keep in orbit, the astronaut cannot. Therefore he will float downwards.

10 BERG AND BROUWER

These quotations also illustrate another common student conception-that a force is required to keep a satellite or rocket moving in an orbit around the earth. This question demonstrated more than any other of the four posed, that a particular correct student response does not guarantee student understanding of the physical situation. In this spaceship question, most of the students choosing the correct response did so on the basis of an alternate conception differing from the currently accepted scientific conception. Further indication of this lack of correspondence between a response and the alternate conception held can be seen in the three student quotations above, in which a particular conception-a force is required in the direction of the motion- lies at the basis of at least three different incorrect responses. Teachers also identified “experience” in the form of movies and television programs to be responsible for many incorrect responses to this question.

The fourth question (Figure 4) showed an astronaut, holding a wrench to one side, standing on a flat lunar surface. The astronaut is described as gently letting go of the wrench. Students were then asked to indicate which of the diagrams below best showed the direction of the force on the wrench. In the study of Watts and Zylbersztajn (1981) almost 80% of the students tested predicted that the wrench would float or move away from the moon; i.e., fewer than 20% of the students would predict that the wrench would fall to the moon. Similar results were obtained by Ruggiero et al. (1985). When the question was posed to 20 physics teachers, several indicated that the problem was trivial, that all the students would predict that the wrench would fall. On average, the teachers predicted that 73.5% of the students would choose the correct response. Since our teacher interviews were conducted before the student testing, the difference between the teacher predictions and the published research results created considerable uncertainty and we entertained the possibility that our Edmonton students would score much better on this question than students elsewhere. Our results did indeed indicate that a somewhat

No Force

Fig. 4. The force on the wrench released by the man on the moon.

STUDENT ALTERNATE CONCEPTIONS 1 1

TABLE IV

Watts and Edmonton Zylbersztajn Students Planning All Ruggiero et al. Edmonton

London Study to Take Grade Nine Italian Study Teacher Student Response (1981) Physics Science Students (1985) Expectations

Toward moon’s surface 37.2% Away from astronaut 12.6% Away from the moon Almost 17.5% Floats (no force) 21.9% Toward the astronaut 1.6% Other responses 3.3% Total responses (N = 125) (N = 183)

~ ~

28 9% 5% to 45% 13 5% 12.7% 7.0% 22 2% 55% to 95% 6 0%

29 5% 10.6% 1 3 % 0 3% 5 4% 2 15%

(N = 315) (N = 40) (N = 20)

greater percentage of our students identified the acceptable response (especially those who chose to do physics later), but the teacher predictions were shown to be totally incorrect.

The most common conception among the students was that there is no gravity on the moon because there is no air on the moon. Only one teacher was aware of this alternate conception despite the fact that the association of gravity with the “weight of the atmosphere” is historically well known (Brouwer & Singh, 1983). Some typical student comments were as follows:

“There is no air pressure in space, so there is no gravity.”

“The moon has no atmosphere, therefore it has no gravity.”

A clue to the prevalence of this alternate conception is evident in even some of the correct predictions: “Even though the moon has no air, it still has gravity.”

The most common alternate conception predicted by the teachers was actually the second most common among the students. This was the belief that since the moon is in space, there is no gravity on the moon. One surprising finding is that in the absence of a force of gravity on the wrench over 20% of the students expected the wrench to move away from the moon rather than just float in the place where it had been released. Six of the teachers suggested that space programs and science fiction movies might be responsible for some of these misconceptions.

Roughly 10% of the students and two of the interviewed teachers believed that the moon’s gravity might be too weak to hold down the wrench and that the wrench might fall to the earth, towards the sun, or end up on some other large heavenly body. In this case also, historians of the science will recognize one of the points of contention between early Copernicans and the Ptolemaic astronomers (Hesse, 1965, p. 127).

Teaching Strategies

One of the challenges facing today’s researchers is to develop strategies for teachers’ use in trying to overcome student alternate conceptions. The observed tenacity of these

12 BERG AND BROUWER

alternate conceptions over different age groups, both before and after instruction, highlights the need for the discovery of effective strategies.

Failure to induce conceptual change has been observed in a number of cases where excellent teachers were using a variety of different teaching strategies (Anderson & Smith, 1985). In studying 14 different teachers the researchers found a common trait in all of their instructional strategies-the teachers failed to create conceptual conflict between the students’ alternate conceptions and the desired conception.

Hewson and Hewson (1983) and Zietsman and Hewson (1986) give some evidence that instructional strategies specifically designed to lead students from their existing conceptions to new conceptions were significantly more effective than traditional teaching strategies.

Mitchell and Baird (1986) report frequent success in the restructuring of student physics conceptions to the desired Newtonian conceptions by using a process of “con- ceptual conflict.” In this method demonstrations or conceptual puzzles are set up in class and students are asked to predict the outcome using their own conceptions. After students have committed themselves to a prediction, the experiment, or activity is carried out, and the results are compared to the student predictions. An extensive analysis of the implications of the student conceptions is camed out followed by the introduction of the desired conception. Mitchell and Baird report the greatest success with students whose own alternate conceptions have failed miserably in predicting the outcome.

Four years prior to the Mitchell and Baird work, Posner, Strike, Hewson, and Gertzog ( 1982) outlined a number of conditions they felt were needed to convince a student that their conceptions were not satisfactory and should be replaced. First of all it was deemed to be necessary to create dissatisfaction with existing conceptions, by allowing students to witness events where the observations came into direct conflict with predictions based on their conceptions. Only after students have faced such a conceptual conflict should the new conception be introduced. Posner, Strike, Hewson, and Gertzog (1982) outlined three characteristics of such a new conception. First, it should be intelligible, so that the students are able to apply the concept easily to the situation posed. It is felt that the gap between conceptions should not be too extensive, in order to minimize the danger of students using the teacher’s concepts inside the school while retaining their previous conceptions outside the school (Gilbert, Watts & Osborne, 1982; West & Pines, 1984).

The second trait of the replacement conception is that it must appear initially plausible and consistent with aspects of other knowledge held by students. It is important that this new strategy has the capacity to solve problems that were dealt with unsatisfactonly by the previous concept. Thus, it becomes crucial for teachers to present students with situations which demonstrate the “fruitfulness” of the replacement conception.

The last trait mentioned by Posner, Strike, Hewson, and Gertzog (1982) is that the replacement conception must be generalizable to other situations. This implies that teachers should assist and help the students apply the replacement concept to familiar and new situations.

A number of current researchers have also called for the development of evaluation procedures that identify whether or not students have acquired the desired conceptions (Hewitt, 1983; Brouwer, 1984). It is clear from this study and other research that students can be successful on knowledge-based questions or numerical problem solving without having integrated the desired scientific conception into their conceptual structure.

STUDENT ALTERNATE CONCEPTIONS 13

Lawson (1988) also emphasizes the need for cognitive conflict in order to facilitate the acquisition of new biological concepts among young children.

Other researchers have urged a greater integration of the historical development of physics into physics teaching. McCloskey (1983), Brouwer and Singh (1983), and Wandersee (1985) have provided evidence that student alternate conceptions in physics have often had a prominent place in the history of physics and that a knowledge of such a conceptual history might help to anticipate student conceptual difficulties in physics.

In the present study, the Edmonton high school physics teachers indicated that they would use four main teaching strategies when teaching the subject areas from which the questions were drawn. These four strategies (listed from most common to least common) are expository, demonstration, analogies and questioning-discussion.

Expository teaching strategies accounted for almost half of the indicated teaching strategies. Most expository strategies were coupled with other strategies but there were a number of teachers who indicated just an expository approach. For example,

What is causing the force? Just talk about it and make sure they understand it’s only gravity and gravity doesn’t make things go up; it pulls things towards the center of the earth.

It was most common to have teachers suggest an approach involving exposition combined with other strategies. For example:

Well, I would say, “well, there’s gravity on the moon, just like there is on the earth you know. Any mass exerts a force. If I had a spanner here and let go it’ll fall to the ground. Why should it be different on the moon since you also have gravity on the moon. , .”

The majority of teachers also suggested demonstrations as a preferred stratagem for teaching at least one of the conceptual areas. An example of one used in the study of circular motion is

Oh yeh. I started spinning things around and we had a real barrage of objects flying around the room, bouncing off the walls and you know I was spinning them slowly and spinning them quickly. . . They came across the room in a very straight pathway and that convinced them . . . I have some students they still don’t believe it and they’ll argue to their death just about, real interesting people. Well, it convinced almost all of them.

Fewer then 10% of the teachers indicated an approach involving questioning and discussion, such as the following example:

I draw a force diagram on he board and 1 analyze it. What causes the object to go up? Is the force still acting that is causing the object to go up once it is released from the hand? I discuss this and draw the diagrams on the board to see as well a show them physical motion of throwing an object up. . . To see whether the student can understand that the force that was acting from the hand has stopped the minute that you in turn release the ball. The only thing that could possibly be after that is the force of gravity that is acting on it. I then ask them what causes

14 BERG AND BROUWER

the object to slow down? What causes the object to come back down? What causes the object to accelerate on the way back down? So by asking pertinent questions in that particular regard I clarify some of the difficulties that the student might have had.

Analogies and metaphors were described by Posner et al. (1982) as a means to suggest new ideas to students and to make them intelligible. In this context, the Edmonton high school physics teachers said that they would use analogies to present conceptually similar situations to the students, and thus associate some of the student experiences to the desired conception.

Almost 85% of the analogies discussed with the teachers involved the two circular- motion questions. Although most of the analogies mentioned by the teachers tended to be brief, two of the more detailed are as follows:

You just talk to them about what happens if you ride a bike without a fender, without a mud guard and through a puddle. . . How come when 1 am driving a car and suddenly I lose control, I end up in the ditch? You see here’s the road, this way, you were trying to go around the curve and you end up in the ditch. . .

and, in the example of the astronaut in the orbiting spaceship:

If you have a cup of water and you punch a hole in the cup the water will stream out and they all know that. Why is the water going to stream out? Because of its weight pushing it down; they all know that, so, when you drop the cup what will happen, well, somebody always guesses, the water will stop leaking out, and they know what to watch for so I stand on the counter and drop it , and when they know what to watch for they see that it stops leaking on the way down. . . Then, I can see some lights coming on and some eyeballs clicking open and they realize that the water and the cup are falling together, and that’s why there’s no force betwccn them, and then we talk about ships in orbit and it helps to bring it together. . . They are falling together and, therefore, he should be over here, with the ship, as long as he doesn’t push off, like the cup and the water, the two are falling together.

Of the Edmonton high school physics teachers planning to use a strategy of questioning and discussion, only three indicated that they would direct their instruction at the alternate conceptions. Two of these teachers stated the need to work out explicitly the implications of the student-held conceptions while the third would direct some questions at the alternate conceptions.

Of the remaining strategies, only one stands out. One teacher recalls holding an alternate conception f rom childhood and having it shattered by experience. As this teacher explained his teaching strategy for the rotating ball on a string (Figure 1):

It’s a relatively difficult one to give them a nice demo . . . you can spin things around your head and cut the cord or something like that but I imagine things would happen too fast for that to be of any use. I like to use a little anecdote because this particular thing happened to me when I was a kid. My friend and 1 had been playing on a merry-go-round but had rigged it up with a poplar pole so that the merry-go-round had a radius of maybe 25 feet instead of the usual 4-5 feet. He started pushing this thing on the inside, and I’m sitting on the end of the poplar pole going about nineteen times as fast (an exaggeration) and I decided that

STUDENT ALTERNATE CONCEPTIONS 15

this was more than 1 could stand, so I decided to let go. At the time I let go I had no clear idea what would happen to me, perhaps I would land on my feet, run a few steps and slow down. In actual fact I went sailing straight out and landed in a bush. Ok, I didn’t go straight out this way, and I didn’t go inward, but the last thing I remember before I let go was this patch of bush straight ahead of me. So it was like a revelation, 1 suddenly understood what would happen if you were traveling in a circle and let go, you move straight in the direction you were going. I know it’s only anecdotal but it seems to convince students better than a demo or doing the mathematical derivation.

This teacher had experienced that something which was “only anecdotal” had the power of achieving something teachers have not always been able to achieve by logical mathematical derivations or carefully designed experiments. Perhaps the anecdote functioned as an imaginative base to which the fundamental conceptions concerning circular motion could be anchored.

A few of the teachers, though unfamiliar with recent research on alternate conceptions, expressed awareness of the tenacity of student-held conceptions. As one of the teachers stated:

Now, unfortunately, I never feel terribly successful about that: I wish I had some other ideas. Because we can do all kinds of this stuff and then at the end of the unit I give them a question; and I say “Plot the speed-time graph of a ball thrown into the air.” Well, they give me all kinds of things, nobody ever gets this. When I show them at the end of the test I get arguments; not just acceptance but arguments, resistance; so I know that it’s time to move on but we’re certainly not finished our job here, but it’s time to go on, anyway. And I get resistance, and the resistance comes from the more vocal students, of course, but often the brighter ones. . .

Clearly, using the teaching strategies outlined by the Edmonton teachers during the interviews, only limited success in creating conceptual change is to be expected. Many of the teachers appeared to be unaware of the strength with which students hold on to their own conceptions concerning natural events. The teachers were generally unaware of current research into conceptual change, although experience and reflection had made a few of the teachers aware of the difficulties in teaching certain fundamental concepts.

Conclusions

This study attempted to discern teacher awareness of student alternate conceptions and teaching strategies used when encountering alternate conceptions in the areas of rotational motion and gravity.

Research Question I. Do the Edmonton high school entry-level students hold the same alternate conceptions that have been identified in previous research in the areas of force and gravity?

All student alternate conceptions found in previous research were also present in this study in similar proportions, with the following exceptions:

1. New alternate conceptions were identified that have not been discussed in previous research, mostly in the area of rotational mechanics. In the whirling

16 BERG AND BROUWER

ball example, a number of students suggested that a spin would be imparted to an object moving in a circular path. This spin would then affect the motion of the object, causing it to move in a curved path. A much larger percentage of students planning to take physics were able to predict correctly the results of the space-based problems than those students not intending to take physics. A large percentage of students correctly predicting the outcome of the circular motion questions, which were also used in previous research, did so on the basis of “incorrect” alternate conceptions. Since not all students were able to give reasons for their predictions the exact percentages are not available.

2.

3.

Research Question 2 . Are senior high school teachers of physics aware of student alternate conceptions in the conceptual areas of force and gravity?

The Edmonton senior high school physics teachers were relatively unaware of the alternate conceptions used by their students prior to instruction. They were least aware of alternate conceptions regarding gravity.

As a group they were able to identify almost every student alternate conception found in previous research and in this study. Individually, each identified only a few of the total number found in student answers to the four questions.

It was found that over one third of the teachers held one or more alternate conceptions themselves. It is likely that some of those alternate conceptions have been passed on to students, as they were related to phenomena commonly discussed during a high school physics course. Two teachers expressed frustration over the difficulty in ridding their students of what they perceived to be incorrect conceptions, which were in fact correct.

Do high school physics teachers have teaching strategies to deal with student alternate conceptions, in the areas of force and gravity, that would be considered effective according to current research?

Teaching strategies proposed by the teachers fell into the following categories; expository (46.7%), demonstration of the desired conception (20.0%), analogies (17.8%), and questioning with general discussion (8.9%).

Teaching strategies proposed by the Edmonton senior high school physics teachers would all be classified (Posner et al., 1982) as unsuccessful in accomplishing conceptual exchange. Almost all teachers presented the conception they believed to be correct directly to the student with few allowing the students to predict the outcome of some discrepant event, in an attempt to create dissatisfaction with their personal conception. None of the teachers indicated a necessity to generalize the conceptions to other phenomena in order to prevent compartmentalization. Although three of the 20 physics teachers showed some awareness of research into student alternate conceptions, the others were almost totally unfamiliar with current research in teaching strategies to promote conceptual change.

Our results on teacher awareness of student alternate conceptions are in good agreement with earlier results (Watts & Zylbersztajn, 198 1) that British science teachers were not very good at predicting student alternate conceptions regarding force, gravity, and weight. Our results are also consistent with those of Osborne, Bell, and Gilbert (1983), who found that teachers were largely unaware of children’s science.

One clear implication of our study is that Edmonton physics teachers are almost totally unaware of research on alternate conceptions. Since the study was carried out we have scheduled a number of in-service and preservice activities in order to acquaint science teachers with this important area of research.

Research Question 3.

STUDENT ALTERNATE CONCEPTIONS 17

References

Anderson, B. (1986). The experiential Gestalt of causation: A common core to pupils’ preconceptions in science. European Journal of Science Education, 8(2),

Anderson, C. & Smith, E. (1985). Children’s preconceptions and content-area textbooks. Comprehension Instruction: Perspectives and Suggestions. New York: Longman, Inc.

Arons, A. (198 1). Thinking, reasoning and understanding in introductory physics courses. Physics Teacher, 166- 172.

Ausubel, D. (1968). Educational Psychology. New York: Holt, Rinehart and Winston.

Brouwer, W. (1984). Problem posing physics: a conceptual approach. American Journal of Physics, 52(7), 602-607.

Brouwer, W. & Singh, A. (1983). The historical approach to science teaching. Physics Teacher, 230-236.

Champagne, A., Gunstone, R. & Klopfer, L. (1983). Naive knowledge and science learning. Research in Science and Technological Education 1(2), 173- 183.

Clough, E., Driver, R. & Wood-Robinson, C. (1987). How do children’s scientific ideas change over time? School Science Review, 69, 255-267.

Driver, R. (1981). Pupils’ alternate frameworks in science. European Journal of Science Education, 3(1), 93-101.

Erickson, G. (1979). Children’s conceptions of heat and temperature. Science Education, 63(2), 221 -230.

Galileo, G. (1632). Dialogue Concerning the Two Chief World Systems (tr. Stillman Drake). Chicago, IL: University of Chicago Press, 1970, p. 164.

Galileo, G. (1638), Dialogues Concerning Two New Sciences (tr. Henry Crewe and Alfonso de Salvio) New York: Dover Publications, 1954, p. 166.

Gilbert, J. & Watts, D. (1983). “Concepts, misconceptions and alternative con- ceptions: changing perspectives in science education. Studies in Science Education, 10, 61-98.

Gilbert, J., Watts, D. & Osborne, R. (1982). “Students’ Conceptions of Ideas in Mechanics.” Physics Education, 17, 62-66.

Gunstone, R. & White, R. (1981). Understanding of gravity. Science Education,

Hart, C. (1987). A teaching sequence for introducing forces to year 11 physics

Hashweh, M. (1988). Descriptive studies of students’ conceptions in science.

Hesse, M.B. (1965). Forces and Fields. Totowa, NJ: Littlefield, Adams & Co.,

Hewitt, P. (1983). “Millikan Lecture 1982: The missing essential-a conceptual understanding of physics. American Journal of Physics, 51, 305-31 1.

Hewson, M.G. & Hewson, P.W. (1983). “Effect of instruction using students’ prior knowledge and conceptual change strategies in science learning. Journal of Research in Science Teaching, 20(8), 731-743.

Lambert, P. (1981). Student preconceptions in introductory high school physics. Unpublished master’s thesis, University of Alberta, Edmonton, Alberta.

Lawson, A. (1988). The acquisition of biological knowledge during childhood; conflict or tabula rasa. Journal of Research in Science Teaching, 25(3), 185-189.

155-171.

65, 291-299.

students. Australian Science Teachers Journal, 33( l) , 25-28.

Journal of Research in Science Teaching, 25(2), 121-134.

pp. 157-188.

18 BERG AND BROUWER

McCloskey, M. (1983). Intuitive physics. Scientijc American, 248(4), 122- 130. McCloskey, M. , Carmazza, A . & Green, B . (1980). Curvilinear motion in the

absence of external force: naive beliefs about motion of objects. Science, 210, 1139-1 141.

Minstrell, J . (1982). Explaining the “at rest” condition of an object. Physics Teacher, 10-14.

Mitchell, I. & Baird, J . (1986). Teaching, learning and the curriculum-1: the influence of content in science. Research in Science Education, 16, 135-140.

Osborne, R. (1982). Science education: where do we start?. Australian Science Teachers Journal, 28(1), 21 -30.

Osborne, R., Bell, B . & Gilbert, J . (1983). Science teaching and children’s ideas of the world. European Journal of Science Education, 5(1), 1-14.

Osborne, R. & Gilbert, J . (1980). A technique for exploring students’ views of the world. Physics Education, 15, 376-379.

Pope, M. & Gilbert, J . (1983). Explanation and metaphor in: some empirical questions in science education? European Journal of Science Education, 5(3), 249- 261.

Posner, G., Strike, K . , Hewson, P. & Gertzog, W. (1982). Accommodation of a scientific conception: towards a theory of conceptual change. Science Education, 66(2),

Ruggiero, S., Minzoni, S. , Cartelli, A , , Alighieri, S., Dupre, F. & Vicentini- Missoni, M. (1985). Weight, gravity and air pressure: mental representations by Italian middle school pupils. European Journal of Science Education, 7, 181- 194.

Shuell, T. (1987). Cognitive psychology and conceptual change: implications for teaching science. Science Education, 71(2), 239-250.

Stepans, J . , Beiswenger, R. & Dyche, S. (1970). Misconceptions die hard. The Science Teacher, 37, 65-69.

Wandersee, J . (1985). Can the history of science help science educators anticipate students’ misconceptions?. Journal of Research in Science Teaching, 23(7), 58 1-597.

Watts, D. (1982). Gravity-don’t take it for granted. Physics Education, 17(5). Watts, D. (1983). A study of schoolchildren’s alternate frameworks of the concept

of force. European Journal of Science Teaching, 5(2), 217-230. Watts, D. & Zylbersztajn, A. (1981). A survey of some children’s ideas about

force. Physics Education, 15, 360-365. West, L. & Pines, L. (1984). An interpretation of research in ‘conceptual under-

standing’ within a source of knowledge framework. Research in Science Education,

Zietsman, A.l. & Hewson, P.W. (1986). Effect of instruction using micro-computer simulations and conceptual change strategies on science learning. Journal of Research in Science Teaching, 23( l), 27-39.

21 1-227.

14, 47-56.

Manuscript accepted December IS, 1989,