How Students Learn History, Mathematics, and Science in the Classroom (2005) / Chapter Skim
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10 Teaching to Promote the Development of Scientific Knowledge and Reasoning About Light at the Elementary School Level
10 Teaching to Promote the Development of Scientific Knowledge and Reasoning About Light at the Elementary School Level
Pages 421-474
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From page 421... ...
How do we help students develop scientific ideas and ways of knowing? 1 Introducing children to the culture of science -- its types of reasoning, tools of observation and measurement, and standards of evidence, as well as the values and beliefs underlying the production of scientific knowledge -- is a major instructional challenge.
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From page 422... ...
The study of light gives children an accessible opportunity to see the world differently and to challenge their existing conceptions. We see the world around us because light reflects from objects to our eyes, and yet we do not sense that what we see is the result of reflected light.
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From page 423... ...
encouraging children to engage in the kind of metacognitive questioning of their own thinking that is requisite to scientific practice. Conceptual Understanding How People Learn suggests that learning for understanding requires the organization of knowledge around core concepts.
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From page 424... ...
Dark or black objects mainly absorb light; light or white objects mainly reflect light. There is an inverse relationship between light reflected from and absorbed by an object: more reflected light means less absorbed light.
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From page 425... ...
A very common belief is that light reflects only from shiny objects, such as a mirror or shiny metals. This is hardly surprising; reflections from shiny objects are strikingly obvious, while observing reflection from objects with no apparent shine requires a tool (e.g., a simple device such as a piece of paper strategically placed to show reflected light, or a more sophisticated device such as an electronic meter that measures light energy)
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From page 426... ...
Science, however, is about questioning -- even when something seems obvious -- because explanation is at the heart of scientific activity. Thus the search for an explanation for why shiny objects reflect light must include an answer to the question of why nonshiny objects do not.
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From page 427... ...
Students are expected to report on knowledge claims they feel confident in making and providing evidence for those claims from the data they collected during investigation. This expectation lends accountability to students' investigative activity that is often absent when they are simply expected to observe phenomena.
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From page 428... ...
Cycles focused on developing knowledge claims about empirical relationships generally precede cycles in the same topic area focused on developing explanations for those relationships. Thinking and discussing explanations may occur in other cycles, but the focus of the cycle repre sented by the inner loop is on testing explanations.
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From page 429... ...
For example, when students describe knowing something about the physical world but indicate that their knowledge did not arise from observation or direct experience, the teacher might ask them to think about what they have observed that might be the kind of evidence scientists would expect to have. When students do provide evidence, the teacher might ask them questions about that evidence such as those above, reflecting the norm that systematic study under controlled conditions is a hallmark of the practice of science, and that evidence not obtained under those conditions would lead scientific thinkers to be skeptical about the knowledge claim.
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From page 430... ...
. For example, we observed a group of third graders studying light who had numerous questions about black holes, the speed of light, and light sources on different planets, all of which they decided were best pursued through second-hand investigation.
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From page 431... ...
The variation in views of light exhibited by the students provided a reason to investigate to determine the accuracy of the ideas and the relationships among them. TABLE 10-1 Fourth Graders' Initial Ideas About Light Light travels.
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From page 432... ...
Like, in the first hand, the white light blends with .
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From page 433... ...
I read in this book that when colored light reflects off, like, the same color, that it'll reflect off that.
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From page 434... ...
Because the object is transparent, students are not surprised to see light through it, but they may be surprised that the light goes through at an angle (refraction) , and they are surprised that light also reflects off the block where it enters and where the refracted light exits the block.
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From page 435... ...
These actions support students' metacognitive awareness regarding the questioninvestigation relationship. We think of investigation in classrooms as addressing how students should interact with materials, as well as with one another (when investigation is carried out by groups of students)
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From page 436... ...
She knew that not all the children had made shadows during their exploration, so she used part of the discussion in this phase to ascertain students' understanding of how to put objects in the light to make shadows. She showed the class how the materi als would be set up, with a light source placed a couple of feet from a wall and a piece of poster paper taped on the wall to allow them to draw the shadows they observed.
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From page 437... ...
Ms. Lacey also introduced a new tool to the students: a small rectangular piece of white construction paper, which she called a "light catcher." This tool functioned as a screen to look for reflected or transmitted light.
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From page 438... ...
Students were divided on whether they thought this was possible, which gave them a reason to investigate and supported them in realizing the need to be thorough in observing light with each object. Sec ond, she asked students how they might provide evidence that light did not interact in particular ways with an object.
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From page 439... ...
Thus they described light as only "going through" a piece of clear, colorless plastic wrap even though we could see bright spots of light on the front of the wrap indicating reflected light. Furthermore, students described light as only "being blocked" from a piece of cardboard even though a disc of light the size of the flashlight beam could be seen on the back of the piece of cardboard, indicating that light was going through it.22 The teacher determines whether and when to prompt students' awareness of the ways in which their prior knowledge may be influencing their observations.
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From page 440... ...
Kingsley's class are investigating reflection from a mirror. Their initial conflict is due to Brian's interest in placing the mirror so that its back faces the light source.
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From page 441... ...
Amanda But the mirror [forcefully places the mirror on their drawing paper] has to face the light source [forceful gesture toward light source]
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From page 442... ...
From this step, stu dents make knowledge claims, just as scientists would. That is, they make claims about the physical world, using the patterns they identified to gener ate those claims.
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From page 443... ...
The Prepare-to-Report Phase Description As the activity shifts to a focus on the public sharing of one's findings from investigation (reporting phase) , the role of the class as a community of scientific thinkers takes on new meaning.
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From page 444... ...
In the scientific community, for example, there is an expectation that relationships will be stated precisely and backed by unam biguous and reliable data. It should also be recognized that claims can be stated in the negative, thus indicating a relationship that is claimed to be inaccurate -- for example, the brightness of the light source does not affect whether light reflects from an object.
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From page 445... ...
(absorbed) Clear glass dim light bright light light shadow Purple glass dim purple light bright purple light dark purple shadow Silver wrap bright light no light dark shadow White plastic sheet dim light medium light medium shadow White typing paper bright light dim light medium shadow Black felt no light no light very dark shadow Orange cardboard dim orange light dim reddish light dark shadow Reorganized Data Table and Simplified Observations: On Light Catcher On Back On Light Catcher in Front of Object of Object Behind Object Object (reflected)
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From page 446... ...
The following excerpt from an investigation of light by third graders shows a typical teacherstudent interaction as students attempted to generate knowledge claims.25 The students were working with light boxes producing narrow beams of light and had been given latitude regarding which questions -- identified during the engagement phase -- they would like to study. As a result, different groups of students investigated with different types of materials.
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From page 447... ...
Ms. Sutton So if it's a mirror, the light goes in another direction, or reflects off.
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From page 448... ...
, public reports re quire students to make and defend statements about their understandings, and provide occasions for examining their own thinking and sense making as well as that of others.26 In addition, when students publicly share their results, the need for vocabulary and a common language to communicate ideas becomes salient. Thus, there is an important opportunity for the teacher to support and guide students in the use of scientific terms to facilitate their communication.
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From page 449... ...
The reporting phase culminates with the whole class discussing the claims that have been shared to determine which if any have sufficiently convincing evidence (and a lack of contradictory evidence) to elevate them to the status of "class claim" -- indicating that there is class consensus about the validity of the claim.
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From page 450... ...
Lacey's introduction of the class claim chart sends an important message about the dynamic nature of the inquiry process: reporting is not a culminating activity; it is part of an ongoing activity, the next phase of which will be shaped by what has just transpired. Her decision to alert students to the presence of conflicting ideas provides an authentic purpose for paying attention to one another during the reporting phase and stimulated metacognition.
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From page 451... ...
While this decision has limitations with respect to developing scientific knowledge about light, it has the advantage of giving the students opportunity and responsibility to examine one another's thinking with respect to the norms and conventions of scientific practice, as illustrated by Bobby's pressing the girls to address how they know light is a gas. Such questions can provide opportunities for students particularly interested in a question to pursue it outside of class, or resources might be brought into the class (books or descriptions downloaded from the Internet)
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From page 452... ...
In the second excerpt, a student struggles to make sense of the claim that light reflects and goes through.
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From page 453... ...
The bridging could go as far as examining reflection from black felt, a material students are initially quite sure does not reflect light, but can be observed to do so if the room is dark enough.31 Another approach to addressing the nonacceptance of claims that contradict everyday experience is to tell students that part of learning science means developing new conceptions of reality.32 This does not necessarily mean discarding existing ideas.33 However, it does mean that students need to recognize that in a science context, the cultural beliefs and practices that guide knowledge production in the scientific community dictate what knowledge is valued and accepted and hence is considered scientific knowledge,34 and that they need to operate accordingly in their knowledge-building activity during science instruction. Despite the challenge of accepting claims that are initially counter to everyday thinking, we have regularly observed students, even very young children, developing new ideas that are counter to their initial thinking.
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From page 454... ...
454 HOW STUDENTS LEARN: SCIENCEIN THECLASSROOM following example comes from Ms. Kingsley's kindergarten class during their study of light and shadows.
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From page 455... ...
These texts are modeled after the notebook of a scientist and so are referred to as notebook texts. They consist of excerpts from the notebook of a fictitious scientist, Lesley Park, who uses her notebook to "think aloud" regarding the inquiry in which she is engaged, sharing with the reader her observations of the phenomenon she is studying, the way in which she has modeled that phenomenon, the nature of her investigation, the data collected in the course of her investigation, and the knowledge claims suggested by the data.38 We share excerpts from this instruction to illustrate how text can be approached in an inquiry-based fashion to support students' engagement in scientific reasoning and what role the teacher plays in such activity.
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From page 456... ...
To un derstand any of the other findings in this table, it was important for the students to recognize that the amount of light from the light source (the flashlight) was "ten candles." This discussion, however, led several students to wonder about this unit of measure.
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From page 457... ...
Determining how much evidence is enough to make a broad claim confidently, such as "all objects reflect and absorb light," is fundamental to scientific problem solving. In the following excerpt, the students entertain other possible explanations for the differences between their findings and Lesley's.
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From page 458... ...
We thought we had some transmitted light, too. She's not getting -- detecting that, is she, with her light meter?
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From page 459... ...
The first two are examples of instances in which students questioned the generality of Lesley's claim that "all objects reflect and absorb light." In the first instance, Kit interjects, "I think that she says `all' too much. Like she could just say `most' or she could test more objects because `all' is kind of a lot because she only tested like, seven." Ms.
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From page 460... ...
The classroom community determines the fate of any knowledge claim generated by a group. Within and across each cycle, knowledge claims are generated, tested, refuted, tweaked, embraced, discarded, and ignored.
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From page 461... ...
The final claim, while still in the running, was not accepted by the class, but neither was it rejected. This progression of events with the community knowledge claims resulting from each cycle is like threads that when woven together create the fabric of scientific knowledge and reasoning on the topic of study.
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From page 462... ...
We have argued40 that the "threads that bind" take the form of explicit attention to the relationships among knowledge claims. Conclusions from How People Learn tell us that the formulation of a conceptual framework is a hallmark of developing deep understanding, and that a focus on the development of deep understanding is one of the prin ciples distinguishing school reform efforts that result in increases in student achievement from those that do not.41 The development of organized knowledge is key to the formulation of conceptual frameworks.
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From page 463... ...
During reporting, they made statements such as: "Light can go through glass if it's clear enough," "Light reflects off mirrors and shiny materials, too," and "We had a solid thing here. It just stopped at the object.
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From page 464... ...
. R or 1 THING A or SOME T LIGHT R+T INTERACTS WITH SOME 2 THINGS R+A MATERIALS SOME T+A NOT 3 THINGS R+T+A 4 THINGS R+T+block+A block=A FIGURE 10-5 Community knowledge from the second cycle of investigation (first-hand)
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From page 465... ...
Andy Corey? R CAN DO A T LIGHT INTERACTS WITH ALWAYS 2 THINGS R+A MATERIALS SOME 3 THINGS R+T+A FIGURE 10-6 Community knowledge from the third cycle of investigation (second-hand)
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From page 466... ...
and a narrowing of the possible relationships that can occur when light interacts with matter: light always reflects and is absorbed. Lesley's quantitative data about the amount of reflection and transmis sion of light from an object as measured by a light meter supported addi tional conversation about the issue of quantitative relationships raised by one group in the previous cycle.
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From page 467... ...
But we know that for such a claim -- that light reflects off all materials -- many experiences may be needed for that knowledge to be robust. Relationships such as this for which we have no direct experience or that are counterintuitive (we see reflected light from objects, not the objects themselves)
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From page 468... ...
Pedagogical content knowledge also includes knowledge of curriculum materials that are particularly effec tive for teaching particular topics. A still valuable resource for the study of light in the elementary grades is the Optics kit mentioned earlier that is part of Elementary Science Study curriculum materials developed in the 1960s.
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From page 469... ...
When and how to employ particular strategies in the service of supporting such knowledge building is a different issue, but the topic-specific knowledge for teaching that is identified as pedagogical content knowledge is a necessary element if students are to achieve the standards we have set. CONCLUSION Science instruction provides a rich context for applying what we know about how people learn.
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From page 470... ...
near a major industrial plant in a town with a state university. Approximately 38 percent of the students in this district pass the state standardized tests, and 63 percent are economically disadvantaged.
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From page 471... ...
They were quite proud to report their evidence that it did indeed reflect light.
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From page 472... ...
International Journal of Science Education, 24(10)
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From page 473... ...
. Nature, sources, and develop ment of pedagogical content knowledge for science teaching.
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From page 474... ...
National Committee on Science Education Standards and Assessment, Center for Science, Mathematics, and Engineering Education. Washington, DC: National Academy Press.
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