Teachers want their students to understand. In order to understand students have to associate new knowledge to that which they already know. Often, however, we teachers seem to be at a loss of achieving this goal, and many of our students resort to the memorization of facts which they seem to forget shortly after the next test or exam. More so, probing shows that this knowledge is disjointed, piecemeal, and fragmented. Research has indicated that the key difference between experts and novices does not lie in the number of concepts in their vocabularies. Rather, the difference lies in the hierarchical and lateral integration of the experts knowledge framework . To help students to organize concepts into a meaningful framework, Novak invented a learning heuristic. He called this heuristic concept mapping .
The heuristic of concept mapping was designed (1) to assist learners in understanding concepts and the relations between them; (2) to establish hierarchical relationships among the concepts; and (3) to recognize the propositional nature of knowledge. We use concept maps in a variety of contexts. Our students map the key concept in an assigned reading, or they represent the findings from a laboratory investigation. Figure 1 shows a concept map which a grade six student completed after several experiments with thermometers. The concept map quite clearly shows that the students not merely remembered simple phrases, but that she could interconnect different aspects of the thermometer into a web of propositions. For this girl, knowledge was not simply a body of disjointed statements and fact-like propositions, but a connected whole.
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We found that working on concept maps encourages students to explain information that they "know" by gut feeling, but which they don't really understand. Encouraging them to make their own ideas explicit, to describe these ideas in their own words, helps students realize that they have not yet constructed a complete understanding; they have to look again, consider the ideas in the context of the initial experiment, and try to connect the ideas to each other and to their prior knowledge. Also, we found that when designing concepts maps, students frequently realize that they don't know how two ideas are related, and this leads them to develop new questions to investigate.
Much of our introduction follows the instruction prepared by Novak and Gowin (1984). We begin our instruction with two lists of words. The first list includes familiar object words, such as car, dog, chair, table, and house. The second list includes event words such as raining, running, thunderstorm, and birthday party. Projecting one list at a time, we ask the children what the words describe until they have identified the lists as describing objects and events. We then introduce the word "concept" as label for both object and event words.
In the next step, we list words such as are, where, then, with, and the. Even without much prompting, our students invariably will come up with the label "linking words" for this set of terms. These terms are used to link pairs of concepts to form propositions, that is, simple sentences that have meaning.
A fourth list of words includes proper nouns such as Toronto, Michael Jordan, Mississippi, Lake Ontario, and Christmas. We help students arrive at the distinction between proper nouns, that is names of specific places, events, and objects on the one hand, and concepts as labels for regularities on the other.
Using concepts from our lists we have children construct several simple sentences. In this way, we show the meaning of a term. To help students understand the importance of sentences for the conveyance of meaning, we ask them the following. "Can you tell me how much I know about basket ball if I say 'Michael Jordan.'" By constructing simple sentences with 'Michael Jordan' we can show that some sentences which express knowledge are correct in that they are shared widely (Michael Jordan is a basketball star), while others are incorrect (Michael Jordan is quarterback).
At this stage, we let students work in groups of three or four because they are of great support to each other. We have children identify the main concepts in an excerpt from a science textbook at the appropriate level. To make the first concept map not too complex, there should not be more than 10 to 12 concepts. So that the students can underline or highlight these concepts, we type out the text rather than using their own textbook. Then we hand to each group of students a sufficient amount of 1.5" x 2" slips of paper on which they write all the concepts they identified. The students rank order these slips with concepts marked on them in order of importance. At this point, they are ready to begin there first concept map.
Using a sample concept map on a different topic projected on the wall, we point out that the most inclusive, the most general concepts appear on top of the concept map. More specific and less general, less inclusive concepts appear further down in the map. We let students read sections of this map so that they can experience how much knowledge can be represented in such a map. With the sample map still projected, the students then proceed to fan out there concept labels on the paper slips, while they talk about how pairs of concepts can be linked. When they are satisfied with their arrangements, students transfer their arrangements to their notebooks. We emphasize the use of pencils, so that they can make changes even as they link concepts.
Our students use concept maps in several different contexts. First, they concept map what they know when they do hands-on activities. Before the students begin their investigations, we have them list the concepts which they already know about the topic. After they have completed their investigation, the students add to their previous list all those which they newly learned. Then they prepare a concept map which includes both their previous concepts and the new ones. In this way, the students experience for themselves how new concepts tie to those that they already had. As such, concept maps fit well into a program that makes use of the Learning Cycle, during which students invent new concepts for which the teacher provided new labels. To help students integrate these new labels into that which they already know, concept mapping is an ideal experience. Figure 2 presents a good example of a grade 6 student's map after an experiment on boiling as one example of a phase change.
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Concept maps are also ideal to help students understand textual materials. We sometimes ask students to read something at home. To give them an incentive in integrating what they read to what they already know, we ask them to make a concept map on their own. To make sure that they have used all the terms they had previously identified, some students prefer to list all the concepts on the margin of their paper. In this way, they can cross off those concepts already used. The concept map in Figure 3 is a map of concept from the Silver Burdett Science 6 textbook (Mallinson, Mallinson, Smallwood, & Valentino, 1985) which summarizes a student's reading on changes of matter.
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We find that concept maps are especially well suited to help students construct an overview of the science content which they learned over a period of time. By providing students with a list of concepts from all the experiments and/or chapters in the reference book, we make sure that the students will map the key concepts. Through concept mapping, the students are then enabled to tie together the various ideas spread throughout the chapters of a unit. While students usually perceive science content as a sequence of topics, this activity helps them to build an integrated framework.
Concept mapping also helps us teachers to organize our thoughts about teaching a unit. It has been shown , concept maps have helped teachers from grade 4-8 to develop science curricula which are hierarchically arranged, integrated, and conceptually driven. For example, the curriculum within which the student activities leading to concept map in Figure 3 were embedded was mapped by the teacher at a larger scale (zoom out) in Figure 4. For each of the concepts, we provide a series of hands-on activities. On the zoom out, we provided an indication of the various lesson topics. We draw a specific concept map for each lesson which contains not only the more abstract concepts, but also details about individual experiments. This detailed map would be very close to that which the students drew in Figure 3. Ideally, the students should have the opportunity to conduct all these investigations on their own, so that the knowledge represented in the map has a solid foundation in the experiences of the students. The concept map aids us to plan the curricular unit, and helps us to assist students in integrating all the hands-on activities into a consistent and meaningful structure.
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In our own work, we have been able to establish the usefulness of concept mapping in several respects  . First, concept mapping in groups helps to engage students in a discourse through which they make sense of their experiences, whether these were hands-on or reading experiences. Second, in order to talk about science concepts to their peers (and the teacher), students have to externalize their own meanings. In the process, they have to evaluate, integrate, and elaborate on their understanding in ways which leads to improve their own comprehension. Third, concept mapping allows students to integrate the various experiences in the elementary science classroom to an integrated, wholistic understanding of science. Finally, concept mapping as a collaborative activity allows us teachers to evaluate both the process and the products of students' comprehension activity: We can observe students as they try to make sense, and we have available the final products of their work to assess this understanding.
For those teachers who want to use concept maps to evaluate students and to assign marks, Novak and Gowin (1984) provided a scoring scheme . Assign one point for each valid link; assign five points for each level of valid hierarchy; and assign ten points for each valid cross-link, that is, for a link which connects various sub-hierarchies. You can divide the students score by that which was produced by a teacher about the same topics. In some cases it can happen that students will achieve a higher score than the teacher's reference map.
If you consistently use concept maps with your students, they will soon understand how and why concept maps are constructed. Figure 5 shows a concept map about concept mapping drawn by one of our grade 6 students. It clearly shows the connections which students make between concepts and events on the one hand, and the experiments on the other. The student also expressed the importance of hierarchy, the relationship between concepts and linking words, the relative freedom in constructing the map ("CONCEPT MAPS can be any SIZE/SHAPE"), and that the concept maps help in meaningful learning.
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We have observed an overwhelmingly positive attitude towards science courses in general and towards concept mapping in specific. In their concept maps about science, the students express that science is fun. They like concept mapping because it shows them how things are connected, and because they can work together in groups. We feel that teaching and learning in the science class or laboratory should be a meaningful experience. Concept maps have become an important tool for both students and teachers in our school to get the most out of our classes. Students know how all the lessons and/or experiences are interconnected and they can make sense of, that is, can wholistically visualize, an otherwise seemingly sequential curriculum. The teachers know how to put all the lessons together so that each one builds on the next in such a manner that the students can construct meaning.
 Chi, M. T. H., Feltovich, P. J., & Glaser, R. (1981). Categorization and representation of physics problems by experts and novices. Cognitive Science, 5, 121-152.
 Novak, J. D. & Gowin, D. B. (1984). Learning how to learn. Cambridge: Cambridge University Press
 Mallinson, G. G., Mallinson, J. B., Smallwood, W. L., & Valentino, C. (1985). Silver Burdett science 6. Morristown, NJ: Silver Burdett Co.
 Roth, W.-M. (1993). Construction sites: Science labs and classrooms. In K. Tobin (Ed.), The practice of constructivism in science education (pp. 145-170). Washington, D.C.: American Association for the Advancement of Science.
 Roth, W.-M., & Roychoudhury, A. (1993). The concept map as a tool for the collaborative construction of knowledge: A microanalysis of high school physics students. Journal of Research in Science Teaching, 30, 503-534.
 Starr, M. L. & Krajcik, J. S. (1990). Concept maps as heuristics for science curriculum development: Toward improvement in process and product. Journal of Research in Science Teaching, 27(10), 987-1000.
Figure 1. A concept map drawn after a several experiments with thermometers
Figure 2. A concept map drawn after one of the experiments on phase changes. Here, boiling was the event observed.
Figure 3. A concept map as a summary of a textbook reading by a sixth grade student.
Figure 4. A concept map for planning the grade six curriculum. Various lessons are indicated on this concept map summarizing the whole unit.
Figure 5. A sixth grader summarizes his experience and knowledge about concept mapping.