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Taking Science to School: Learning and Teaching Science in Grades K-8 Appendixes
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Taking Science to School: Learning and Teaching Science in Grades K-8 This page intentionally left blank.
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Taking Science to School: Learning and Teaching Science in Grades K-8 Appendix A Overview of Learning Progressions for Matter and the Atomic-Molecular Theory
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Taking Science to School: Learning and Teaching Science in Grades K-8 Questions & Big Ideasa Components of Big Ideas K-2 Elaboration of Big Ideas 1. What are things made of and how can we explain their properties? Existence of matter and diversity of material kinds. Objects are made of specific materials. There are different kinds of materials. The same kind of object can be made of different materials. 1. Objectsb are constituted of matter, which exists as many different material kinds. Objects have properties that can be measured and depend on the amount of matter and on the material kinds they are made of. Objects have properties that can be measured and explained. Three important properties are mass, weight, and volume. Objects have certain properties—weight, length, area, and volume—that can be described, compared and measured. (Only preliminary exploration and construction of volume measurement at this time.) Material kinds have characteristic properties that can be measured and explained. The properties of materials can be described and classified. (Only readily observable properties, such as color, hardness, flexibility, are investigated at this time.)
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Taking Science to School: Learning and Teaching Science in Grades K-8 3-5 Elaboration of Big Ideas 6-8 Elaboration of Big Ideas Objects are made of matter that takes up space and has weight. Solids, liquids, and air are forms of matter and share these general properties. There can be invisible pieces of matter (too small to see). There are many different kinds of materials. Matter has mass, volume, and weight (in a gravitational field), and exists in three general phases, solids, liquids, and gas. Materials can be elements, compounds, or mixtures. 1AM. All matter is made of a limited number of different kinds of atoms, which are commonly bonded together in molecules and networks. Each atom takes up space, has mass, and is in constant motion. Weight is an additive property of objects that can be measured (e.g., the weight of an object is the sum of the weight of its parts). Volume is an additive property of an object that can be measured. The weight of an object is a function of its volume and the material it is made of. Mass is a measure of amount of matter and is constant across location; weight is a force, proportional to mass and varies with gravitational field. Solids, liquids, and gases have different properties. 1AM. The mass and weight of an object is explained by the masses and weights of its atoms. The different motions and interactions of atoms in solids, liquids, and gases help explain their different properties. Materials have characteristic properties that are independent of the size of the sample. (Extends knowledge to less obvious properties such as density, flammability, or conductivity at this time.) Materials have characteristic properties independent of size of sample (extends knowledge to include boiling/freezing points and to elaborate on density). 1AM. The properties of materials are determined by the nature, arrangement, and motion of the molecules that they are made of.
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Taking Science to School: Learning and Teaching Science in Grades K-8 Questions & Big Ideas Components of Big Ideas K-2 Elaboration of Big Ideas 2. What changes and what stays the same when things are transformed? Mass and weight are conserved across a broad range of transformations. There are some transformations (e.g., reshaping, breaking into pieces) where the amount of stuff and weight is conserved despite changes in perceptual appearance. 2. Matter can be transformed, but not created or destroyed, through physical and chemical processes. Material kinds stay the same across some transformations and change across others. Material kind stays the same when objects are reshaped or broken into small pieces. Freezing and melting changes some properties of materials but not others.
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Taking Science to School: Learning and Teaching Science in Grades K-8 3-5 Elaboration of Big Ideas 6-8 Elaboration of Big Ideas Matter continues to exist when broken into pieces too tiny to be visible. Amount of matter and weight are conserved across a broader range of transformations (e.g., melting, freezing, and dissolving). Mass and weight (but not volume) are conserved across chemical changes, dissolving, phase change, and thermal expansion. 2AM: Mass and weight are conserved in physical and chemical changes because atoms are neither created nor destroyed. Materials can be changed from solid to liquid (and vice versa) by heating (or cooling) but are still the same kind of material. Combining two or more materials can produce a product with properties different from those of the initial materials. Some transformations involve chemical change (e.g., burning, rusting) in which new substances, as indicated by their different properties, are created. In other changes (e.g., phase change, thermal expansion) materials may change appearance but the substances in them stay the same. 2AM: In chemical changes new substances are formed as atoms are rearranged into new molecules. The atoms themselves remain intact. 2AM: In physical changes, molecules change arrangement and/or motion but remain intact, so the chemical substance remains the same.
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Taking Science to School: Learning and Teaching Science in Grades K-8 Questions & Big Ideas Components of Big Ideas K-2 Elaboration of Big Ideas 3. How do we know? Good measurements provide more reliable and useful information about object properties than commonsense impressions. Measurement involves comparison. Good measurements use iterations of a fixed unit (including fractional parts of that unit) to cover the measured space completely (no gaps). Measurements are more reliable than commonsense impressions. 3. We can learn about the world through measurement, modeling, and argument. Modeling is concerned with capturing key relations among ideas rather than surface appearance. Some properties of objects can be analyzed as the sum of component units. (Students are involved with the implicit modeling of extensive quantities through the creation of measures.) Arguments use reasoning to connect ideas and data. Ideas can be evaluated through observation and measurement. aIn this table, the term “big idea” corresponds to “core idea” used throughout the report. The committee adopted the term core idea to differentiate the learning progressions idea from other initiatives that use the term big idea. bAs mentioned in the text, we use the term “object” in the broad sense to refer to any bounded material entity, not just solids. SOURCE: Smith et al. (2006).
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Taking Science to School: Learning and Teaching Science in Grades K-8 3-5 Elaboration of Big Ideas 6-8 Elaboration of Big Ideas Although measurements are more reliable than commonsense impressions, measurements can be more or less precise and there is always some measurement error. Instruments, such as microscopes, can extend our ability to observe and measure. Our senses respond to combinations of physical properties, rather than isolated ones. For this reason, they are not good measures of those physical properties. Sources of measurement error can be examined and quantified. We can learn about the properties of things through indirect measurement (e.g., water displacement) as well as using powerful tools (microscopes). 3AM. Atoms are too small to see directly with commonly available tools. Graphs, visual models, simple algebraic formulas, or quantitative verbal statements can be used to represent inter-relations among variables and to make predictions about one variable from knowledge of others. Models can propose unseen entities to explain a pattern of data. 3AM: The properties of and changes in atoms and molecules have to be distinguished from the macroscopic properties and phenomena for which they account. Hypotheses and data are distinct. We make stronger arguments for our ideas when they fit a pattern of data rather than simply one observation. We can clarify our ideas by more precisely stating the conditions under which they are true. Good arguments involve getting data that help distinguish between competing explanations. 3AM. We learn about properties of atoms and molecules indirectly, using hypothetico-deductive reasoning.
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