C calcium carbonate CACO3 - a white precipitate that forms in water lines, water heaters and boilers in hard water areas; also known as scale. In some igneous rocks, caverns can be formed by large gas bubbles. A BOD test in which a nitrification inhibitor is added, so that only the carbonaceous oxygen demanding compounds are measured.
The next concept—scale, proportion, and quantity—concerns the sizes of things and the mathematical relationships among disparate elements. The next four concepts—systems and system models, energy and matter flows, structure and function, and stability and change—are interrelated in that the first is illuminated by the other three.
Each concept also stands alone as one that occurs in virtually all areas of science and is an important consideration for engineered systems as well. Regardless of the labels or organizational schemes used in these documents, all of them stress that it is important for students to come to recognize the concepts common to so many areas of science and engineering.
Patterns Patterns exist everywhere—in regularly occurring shapes or structures and in repeating events and relationships. For example, patterns are discernible in the symmetry of flowers and snowflakes, the cycling of the seasons, and the repeated base pairs of DNA.
Noticing patterns is often a first step to organizing and asking scientific questions about why and how the patterns occur. One major use of pattern recognition is in classification, which depends on careful observation of similarities and differences; objects can be classified into groups on the basis of similarities of visible or microscopic features or on the basis of similarities of function.
Such classification is useful in codifying relationships and organizing a multitude of objects or processes into a limited number of groups.
Patterns of similarity and difference and the resulting classifications may change, depending on the scale at which a phenomenon is being observed.
For example, isotopes of a given element are different—they contain different numbers of neutrons—but from the perspective of chemistry they can be classified as equivalent because they have identical patterns of chemical interaction.
Once patterns and variations have been noted, they lead to questions; Page 86 Share Cite Suggested Citation: A Framework for K Science Education: Practices, Crosscutting Concepts, and Core Ideas.
The National Academies Press. Engineers often look for and analyze patterns, too. For example, they may diagnose patterns of failure of a designed system under test in order to improve the design, or they may analyze patterns of daily and seasonal use of power to design a system that can meet the fluctuating needs.
The ways in which data are represented can facilitate pattern recognition and lead to the development of a mathematical representation, which can then be used as a tool in seeking an underlying explanation for what causes the pattern to occur.
For example, biologists studying changes in population abundance of several different species in an ecosystem can notice the correlations between increases and decreases for different species by plotting all of them on the same graph and can eventually find a mathematical expression of the interdependences and food-web relationships that cause these patterns.
Progression Human beings are good at recognizing patterns; indeed, young children begin to recognize patterns in their own lives well before coming to school. They observe, for example, that the sun and the moon follow different patterns of appearance in the sky.
Once they are students, it is important for them to develop ways to recognize, classify, and record patterns in the phenomena they observe.
For example, elementary students can describe and predict the patterns in the seasons of the year; they can observe and record patterns in the similarities and differences between parents and their offspring. Similarly, they can investigate the characteristics that allow classification of animal types e.
These classifications will become more detailed and closer to scientific classifications in the upper elementary grades, when students should also begin to analyze patterns in rates of change—for example, the growth rates of plants under different conditions.
By middle school, students can begin to relate patterns to the nature of microscopic and atomic-level structure—for example, they may note that chemical molecules contain particular ratios of different atoms.
Thus classifications used at one scale may fail or need revision when information from smaller or larger scales is introduced e. Mechanism and Prediction Many of the most compelling and productive questions in science are about why or how something happens.
Today infectious diseases are well understood as being transmitted by the passing of microscopic organisms bacteria or viruses between an infected person and another. A major activity of science is to uncover such causal connections, often with the hope that understanding the mechanisms will enable predictions and, in the case of infectious diseases, the design of preventive measures, treatments, and cures.
Repeating patterns in nature, or events that occur together with regularity, are clues that scientists can use to start exploring causal, or cause-and-effect, relationships, which pervade all the disciplines of science and at all scales.
For example, researchers investigate cause-and-effect mechanisms in the motion of a single object, specific chemical reactions, population changes in an ecosystem or a society, and the development of holes in the polar ozone layers. Any application of science, or any engineered solution to a problem, is dependent on understanding the cause-and-effect relationships between events; the quality of the application or solution often can be improved as knowledge of the relevant relationships is improved.
Identifying cause and effect may seem straightforward in simple cases, such as a bat hitting a ball, but in complex systems causation can be difficult to tease out. It may be conditional, so that A can cause B only if some other factors are in place or within a certain numerical range.
For example, seeds germinate and produce plants but only when the soil is sufficiently moist and warm. Frequently, causation can be described only in a probabilistic fashion—that is, there is some likelihood that one event will lead to another, but a specific outcome cannot be guaranteed.Programme Overview The SIT-Newcastle University (NU) joint degree programme in Chemical Engineering aims to produce graduates who have a clear understanding of Chemical Engineering, combining a sound theoretical grasp of the subject with practical experience and an awareness of their responsibility to society and the environment.
Chemical equilibrium occurs when opposing reactions are proceeding at equal rates. The rate at which the products are formed from the reactants equals the rate at which the reactants are formed from the products. For equilibrium to occur, neither reactants nor products can escape from the system.
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