The backwash effect (also known as the washback effect) is the influence that a test has on the way students are taught (e.g. the teaching mirrors the test because teachers want their students to pass).
What is backwash and how does it work?
Backwash is a type of preventive measure to maintain the conditions of filter media. It is widely used in the field of water treatment, such as sewage treatment and water purification. It involves pumping the water backwards via filter media along with the utilization of compressed air.
What is the backwash effect in education?
The backwash effect can be defined as the direct or indirect effect of examinations on teaching methods. According to the effect of examinations on what we do in the classroom we may refer to 'positive' and 'negative' backwash (Heaton 1990: 170, Hughes 1989: 1).
What is the backwash effect of economic growth?
Backwash Effects. Economic growth provides benefits and costs in the region in which it occurs. It has a positive impact on nearby localities if jobs, population, and wealth spill over into these communities.
Is the backwash effect positive or negative?
However, the backwash effect remains predominantly negative and encourages a model of learning summed up in the left-hand column of Table 1. (Broadly speaking, the two approaches described correspond to left and right brain learningsee, for example, Gerngross and Puchta, 1992.
What is backwash effect in Myrdal theory?
It is an economic development effect suggested by Swedish economist Gunnar Myrdal.It basically means that if one particular area in a country starts growing or developing, it causes people, human capital as well as physical capital (infrastructure, finance, machines etc.)
What is backwash effect in regional planning?
A backwash effect attracts resources such as capital and labor to migrate from less developed peripheral areas to more developed areas, thus expanding regional differences.
What is the difference between spread effect and backwash effect?
'Generally, spread effects are the positive effects of urban proximity for communities, and backwash effects are the negative consequences of proximity.
What is the backwash effect ap human geography?
Ancillary activities: Economic activities that surround and support large-scale industries such as shipping and food service. Backwash effects: The negative effects on one region that result from economic growth within another region.
Do backwash effects outweigh spread effects in the developing countries?
The term "backwash effects" is taken from Gunnar Myrdal; a Swedish economist who observed that backwash effects often outweighed the spread effects that were supposed to transmit economic development from rich to poor countries, or from rich areas within a country to poorer areas.
What is critical growth rate?
There is a critical growth rate of capital stock which makes the growth rate of income equal to growth rate of capital stock. Therefore, the equilibrium position ultimately depends on the rate of accumulation of capital stock in an economy.
What are backwash effects of trade?
The country from which the people emigrate which loses skilled people is known as backwash effect. The country from which the people immigrate which gains skilled people is known as backwash effect.
What is a spread effect?
The spreading effect works to lower fixed costs. As you produce more goods, your fixed costs are spread out over a greater amount of production, reducing the unit cost of each product.
What is the multiplier effect in economics?
The multiplier effect refers to the effect on national income and product of an exogenous increase in demand. For example, suppose that investment demand increases by one. Firms then produce to meet this demand. That the national product has increased means that the national income has increased.
What is a buffer state AP Human Geography?
countries. 3. Buffer State. A relatively small country sandwiched between two larger powers. The existence of buffer states may help to prevent dangerous conflicts between powerful countries.
What is Unit 7 of AP Human Geography about?
Overview of Unit 7 Theories of settlement geography, such as Christaller's central place theory, the rank‐size rule, and the gravity model, are introduced. Quantitative information on such topics as population growth, migration, zones of influence, and employment is used to analyze changes in the urban hierarchy.
What is the multiplier effect ap human geography?
Multiplier effect: Describes the expansion of an area's economic base as a result of the basic and non-basic industries located there. Variable cost: A cost that changes based on the level of output that a business produces.
What is the multiplier effect in economics?
The multiplier effect refers to the effect on national income and product of an exogenous increase in demand. For example, suppose that investment demand increases by one. Firms then produce to meet this demand. That the national product has increased means that the national income has increased.
What do you understand by cumulative causation?
Cumulative causation refers to a change of factors progressing cyclically and cumulatively through reciprocal reinforcement of the factors. There are two genealogies for theories of cumulative causation. In the first genealogy, analytical themes provide the dynamics of the macro economy.
What is reinvestment criteria?
Reinvestment Criteria: This criteria has been given by Walter Galenson and Harvey Leibenstein. It says that allocation of resources will be optimum when the marginal per-capita reinvestment quotient of capital is equalised in its various alternative uses.
How social dualism affects in the developing economies?
Social dualism thus is kind of social disintegration caused by the rise of capitalism in less developed economies. This integration highlights the conflict between the imported social order and the indigenous social order of the underdeveloped economies.
Description
This article assesses the concept of 'backwash' in language teaching. It looks at the consequences of testing on teaching in a broad educational context. It suggests that 'negative backwash' makes good language teaching more difficult.
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'Teach' and 'test' are quite close together in a dictionary, but in testing we do different things from the things we do when we teach.
What is the backwash effect?
The backwash effect can be defined as the direct or indirect effect of examinations on teaching methods. According to the effect of examinations on what we do in the classroom we may refer to 'positive' and 'negative' backwash (Heaton 1990: 170, Hughes 1989: 1).
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ftypes favoured in the particular examination students will be taking: multiple-choice, transformation, or gap-filling. The methodological routine that results from the negative backwash effect in its overt forms is an all too familiar one: presentation of the text followed by questions similar to those in the examination.
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fLead-ins and follow-ups have become standard teaching devices (see Peck 1988: 201, where he refers to them as 'heads and tails'). The pedagogic rationale of a lead-in is to arouse interest and draw on the students' knowledge, thereby making learning 'easier'.
Denying learners' thinking time
fSome learners need more thinking time than others, but conventional testing conditions impose a strict time limit on the production of knowledge. It is not uncommon to hear of highly intelligent people who have failed public examinations because of time constraints, or an inability to adapt their learning style to examination conditions.
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exercises (multiple-choice, etc.] failure weakness errorphobia marks fear anxiety teacher control textbook input judgement mistrust individualism, competition impersonality insensitivity isolated sentences fragments of text form culture-bound text+questions solemnity boredom extrinsic motivation product
What Does Backwash Mean?
Backwash is a type of preventive measure to maintain the conditions of filter media. It is widely used in the field of water treatment, such as sewage treatment and water purification.
How does backwashing work?
It involves pumping the water backwards via filter media along with the utilization of compressed air. Effective backwashing can account for the success of water treating facilities.
What are the effects of oxygen on a loop system?
Oxygen and other physical impurities can cause detrimental conditions within the loop system, resulting in pipe breakdowns and failures in regulators, valves, boilers, controls, fittings and other forms of mechanical equipment . Such malfunctions can increase corrosion, wear and tear as well as buildup of sludge.
How do water treatment filters work?
Some water treatment filters use surface wash systems that break up the heavily clogged, granular media surface layer. Surface wash systems are buried in the top of the filter media or are suspended above the filter media surface. John R. Baylis developed a fixed grid system which consisted of pipes with nozzles that injected jets of water into the filter material during expansion. Rotating arms use jets of water to break up the clogged filter surface and to rotate a movable arm through the filter material. A surface wash step in a backwash cycle usually takes place at the beginning of the filter bed cleaning process. : 199–200 : 357–60
What is backwash cycle?
The backwash cycle is triggered after a set time interval, when the filter effluent turbidity is greater than a treatment guideline or when the differential pressure ( head loss) across the filter exceeds a set value . Water treatment filters that can be backwashed include rapid sand filters, water softening systems, ...
What is backwashing in water treatment?
Backwashing is a form of preventive maintenance so that the filter media can be reused. In water treatment plants, backwashing can be an automated process that is run by local programmable logic controllers (PLCs). The backwash cycle is triggered after a set time interval, when the filter effluent turbidity is greater than a treatment guideline ...
How to backwash a granular media filter?
First, the filter is taken off line and the water is drained to a level that is above the surface of the filter bed. Next , compressed air is pushed up through the filter material causing the filter bed to expand breaking up the compacted filter bed and forcing the accumulated particles into suspension. After the air scour cycle, clean backwash water is forced upwards through the filter bed continuing the filter bed expansion and carrying the particles in suspension into backwash troughs suspended above the filter surface. In some applications, air and water streams are simultaneously pushed upwards through the granular media followed by a rinse water wash. Backwashing continues for a fixed time, or until the turbidity of the backwash water is below an established value. At the end of the backwash cycle, the upward flow of water is terminated and the filter bed settles by gravity into its initial configuration. Water to be filtered is then applied to the filter surface until the filter clogs and the backwash cycle needs to be repeated.
What happens at the end of a backwash cycle?
At the end of the backwash cycle, the upward flow of water is terminated and the filter bed settles by gravity into its initial configuration. Water to be filtered is then applied to the filter surface until the filter clogs and the backwash cycle needs to be repeated.
What is backwashing water?
In terms of water treatment, including water purification and sewage treatment, backwashing refers to pumping water backwards through the filters media , sometimes including intermittent use of compressed air during the process. Backwashing is a form of preventive maintenance so that the filter media can be reused.
Why do water filters fail?
To keep water treatment filters functional, they have to be cleaned periodically to remove particulates. Ineffective backwashing is one of the main reasons that water treatment filters fail.
