Understanding the Basic Characteristics of Maps
The achievement of cartographic understanding has, as a prerequisite, the understanding of the basic characteristics of maps. Scale, map projections, generalization, and symbolization are common to every map and are considered as basic characteristics of maps. Since map literacy is not systematically included in the school curriculum, there are no definite and clear results referring to children's understanding of these basic map concepts. On the other hand, the results of experimental studies give some evidence as regards children's development of concepts associated with the map's basic characteristics.
Map scale is the ratio between the dimensions on the map and on those of reality. According to Piaget, understanding scale requires the understanding of proportionality, concepts achieved at the formal operation stage. Experimental studies in 1999 show that children around 3–4 years old are able to encode proportional distance. Other experiments in 1996 show that 7 year old children make substantial errors in map scale tasks. Also, in another study in 1995, 10 year old children perform worse than children of 11–13 years old in map scale tasks. In 2000, a review study of the above experiments suggests that the contradiction of the results leads to a reconsideration of Piaget's view that scale depends on acquisition of proportionality.
Scale is indicated on maps both in numerical and graphical representations. Graphic scale representations are more useful for young children in distance estimation tasks. In maps addressed to children, different graphic scale representations support different learning levels. In a study in 1971, difficulties and misconceptions were identified in tasks involving children's use of graphic scale such as: confusion by the use of different graphic scales in different maps, difficulty to measure long distances as easily as short ones, inability to understand that the outcome of the measurement is a true distance on the ground, and having problems in countries where the units of measurement are different from those on the map scale.
Through map projections, the spherical surface of the Earth is transformed into a plane. A map projection is a mathematical relationship of geographical coordinates (j, l) and plane coordinates (x, y). Whatever is the mathematical relationship applied to the transformation process, distortions are inevitable. The distortions of the geometric relationships on the sphere (distances, areas, angles, directions), when projected onto the plane, can be controlled by a suitable choice of projection.
Understanding map projections involves constructing the image of the graticule on the map. Children must be able to visualize the form of the graticule and the way it looks from different perspective views. Having achieved this knowledge, children are able to evaluate projections by comparing the geometry of the graticule as it is on the spherical Earth with the grid on the map. Gradually, they come to understand the effects different transformations have on the representation of landmasses as well as the importance of choosing the best projection for a particular map. Children of around 9–11 years of age (depending on different school curricula) are introduced to the concepts of the spherical Earth, the equator, the meridians and parallels. According to Piaget's views, children are able to use coordinates at about 8 years of age. But experiments in 1965 report that children of 10–14 years old have difficulty in using coordinates in mapping tasks. The use of dynamic representations of the globe and its perspectives from different points of view as well as its transformation to a plane through various kinds of map projections can be a strong educational tool for introducing children to the concepts of map projections.
All maps are abstractions of the real world. As the scale gets smaller, the map content gets less. The information portrayed on maps has been chosen according to the scale and the purpose of the map. The chosen information has been subject to the generalization processes, which are: classification (order of features by their attributes), simplification (portrayal of important feature characteristics and elimination of details), exaggeration (enhancement of important characteristics), symbolization (graphical coding of information), and induction (inferences from the interrelations among the features on the map). All the processes of generalization are done by the cartographer, except that of induction for which it is the user who makes logical extensions of the portrayed data, so it depends a lot on the symbolization.
The extent to which the generalized information presented on maps affects the way children interpret maps has not been studied systematically. From the few experimental studies in 1972, 1980, and 1981, there is evidence that children of primary and also of secondary school make misinterpretations, thinking that what is presented on a map is all that exists in the real world. A review study in 1998 recognizes the need for children's introduction to the concept of generalization and to the processes involved in it. Generalization is a key step toward successful map interpretation.
Maps use symbols that stand for the features of the real world they portray. Since 1967, when Jacques Bertin introduced a semiotic approach to cartographic symbolization, cartographers have followed a systematic symbol design, developing typologies of symbol categories. The visual variables (shape, size, orientation, hue, value, chroma, pattern, and texture) were the basis of symbol design assigned to represent quantitative and qualitative variations of the data represented on maps. Although the use of visual variables in symbol design is practically a standard procedure, it has not been considered as a prerequisite knowledge for map use.
Relatively little is known about how young children interpret symbols in maps. According to Piaget, children are able to recognize shape at sometime after 3 years. In 2000, another scholar underlined the fact that children with appropriate guidance could appreciate the symbol–referent relation earlier. It is argued in many experiments that children have greater difficulty in understanding the geometric correspondence than the representational one. In 1996, experiments found that kindergarten children show great variation in symbol identification. Children are able to identify shape variable and show difficulty in color naming. They easily identify both pictorial and abstract line symbols, but they show difficulty with point and area symbols. In other experiments in 1996, very young children aged 5–7 years found pictorial symbols attractive and easier to interpret. Many of them were able to identify abstract symbols using a legend. Size is easily identified. The understanding of color as a variable is cognitively complex, since it requires matching color differences with object characteristics, and this ability improves by age. The level of knowledge (experience) and the level of development (verbal ability and amount of attention) are mentioned as responsible factors.
Elementary school students are gradually exposed to maps that apply abstract symbols and the use of legend. Matching symbols between the legend and the map involves holding the symbol characteristic in memory, so this task develops gradually. Experiments in 1984 show that children understand qualitative symbols first, and quantitative ones later. Size is easily identified as a variable, but it is difficult for children to compare the size of symbols whose area is proportional to a quantity.
School atlases addressed to children older than 11 years comprise thematic maps representing quantities that occur at points, lines, or areas. When quantities occur over an area, a statistical surface is created. The concepts of the statistical surface, of ratio, and proportionality are very important in thematic mapping and a prerequisite knowledge for understanding thematic maps like dot maps, choropleth, and isarithmic common to all school atlases. Experiments in 2003 show that students even of third and fourth year of secondary school do not fully understand the concepts of ratio and proportionality.
The relief can be represented in maps by various methods, such as symbols of stylized form (appear not only on early maps, but also today on maps addressed to very young children), hachuring (lines representing the greatest slope), hill shading, layer tinting (hypsometric coloring), and contouring. Relief can also be represented through perspective pictorial maps (block diagrams, oblique views, and schematic maps). There are two aims of relief representation: first, the visualization of relief by the user when seeing the map as a whole and, second, the interpretation of elevation data. The methods of representation that are effective in the visualization task have poor results in the interpretation tasks. Contouring gives measurable data, but is poor in visualizing. Hill shading gives a realistic visual representation but nonmeasurable data. Recently, topographic maps represent relief by using contours and hill shading, and the result is very effective.
According to Piaget, children are able to understand the relief representation not earlier than 9 years of age and the concept of contouring not earlier than 11 years. In experiments in 1979, it is argued that only at the age of 11 can children interpret simple landforms. But even younger secondary school students show difficulties in height estimation and relief interpretation in cases where contours are not closed. Their performance improves with maps in which contouring is combined with layer tinting. Experiments in 1983 argue that limitations on language development seem to be a serious problem in understanding the relief on maps, since children do not know the geographical terms. The understanding of contours appears to be a difficult task as well. Slope estimation seems to be the most difficult task, even for 14 year olds, as reported in studies in 1979 and 1989. For younger children, three-dimensional models seem to be helpful for an introduction to landscape surfaces, as reported in experiments in 1997. Three-dimensional representations and pictorial maps are more effective for primary school students to visualize landforms.