Specific instructional aims

Students are able to describe the thesis sentence and able to make a short composition.

Sub topics

·         the thesis sentence
·         writing a short essay

The thesis sentence

In writing a short article or an essay, one of the basic steps should be understood is the thesis sentences.  Understanding the thesis sentence is important because it expresses the whole idea contained in the essay.  A thesis sentence indicates the purpose of the composition and conveys the control idea of the article.  Thus, the thesis sentence governs the contents and structure of a whole composition consisting of two or more paragraphs.  Ideally, it is a one-sentence summary of the whole essay.
Different from the topic sentence, i.e. a sentence controlling the idea of a whole paragraph, the thesis sentence is a sentence controlling or governing the whole essays consisting of several paragraphs.
The thesis sentence should be written in the first paragraph of an essay.  It may be the first sentence of the first paragraph, or it may follow an introductory sentence or two leading to the climax of the first paragraph which is the thesis sentence.  For a beginner, writing a thesis sentence is a must.
Thesis sentences vary in numerous ways depending on the content of the subject matter.  They also vary in form: it may be a statement of position, belief, your point of view or other people’s point of point.  The form of thesis sentence is important because of two reasons.  First, it controls or governs the organization of the whole article.  Second, it will serve as a guide where the essay is going to and how to get there.  Thus, much like a good outline, the thesis sentence gives the plans for the essay.
Before writing an outline for an essay, it advisable that the thesis of the composition is clearly designed or jotted down.  This means that the writer must be able to convey an idea or opinion that is to be proved in the article.  Sometimes the writer goes on stating facts in the first paragraph but the writing lacks a thesis or point to be proved.  As the consequence, the essay is devoid of focal point to be proved, because writing everything without a main idea or opinion to be proved will end up saying nothing.
One good suggestion that will help making thesis sentence a clear statement and a good plan for the composition is to divide the thesis sentence into two or three parts.  The first part states the subject and the second or the third part states the supports.  However, the division of the thesis sentence is not limited to two or three supports.  For a long essay, the part of supports may exceed two or three in number, but keep in mind that the essay must discuss each part of the thesis sentence in the order in which it appears in the thesis sentence and each support should be developed sufficiently.
Please have a look at the following thesis sentence: The new agricultural graduate working in rural area must have three admirable qualities: patience, dedication to work, and love for humanity.  This thesis sentence has three part of supports that can be developed further.  The essay should discuss the supporting parts in the order shown below.  However, the topic sentence in each paragraph may vary.
·   Patience with the ignorance of the unskilled farmers (subject) has made the new agricultural graduate an admirable person (controlling idea).  … then you should develop the controlling idea …
·   Dedication to his work (subject) is the outstanding characteristic (controlling idea) of the new agricultural graduate.  …… then you should develop the controlling idea ……
·   Love for humanity (subject) has made the new agricultural graduate enjoys his job (controlling idea) in rural area.  …… then you should develop the controlling idea ……
The most common form of the thesis sentence is that which first states the subject, then indicates the supports.  The subject and the supports can be separated by a transition expression such as because, due to, by, in that, etc. or they can be separated by a colon (:).  Observe the examples below.
1.  His profession (subject) requires three important qualities:  the ability to analyse, an interest in people, and patience with deals (supports).
2.  The topic of his presentation (subject) covers two strategies in plant breeding:  the in vitro and the in vivo approaches (supports).
3.  Most of plant physiological disorders (subject) are caused by nutrient deficiency, high temperature, and low light intensity (supports).
4.  TMV is a dangerous plant virus attacking red peppers (subject) because they are transmitted systemically within plant body (supports).
5.  Vegetative plant propagation (subject) can be done by stem cutting, layerage, and grafting (supports).

Writing a short essay

From the previous lesson, you have learned the function of a thesis sentence:
·   it serves as a guide to the content and organization of an essay.
·   it may be the only sentence in the introductory paragraph, or it may follow a sentence or two leading to the climax (the thesis sentence) of the first paragraph of the essay.
·   it may be divided into one subject plus two or three support parts that should be elaborated in the following paragraphs in the same order it appears in the thesis sentence.
Please have a look at the following outline of an essay on environmental factors affecting stomatal movements.

Environmental Effects on Stomates
First paragraph:  Thesis sentence:  Many factors influence stomatal apertures, and any theory purporting to explain guard-cell action must account for this effects: light, CO2 in the leaves, atmospheric humidity, water potential in the leaves and temperature.  Of these factors, CO2 is considered to have the most direct effect on opening and closing of the stomates.
Second paragraph:  Topic sentence:  Stomates of most plants open at sunrise and close at darkness, allowing entry of the CO2 used in photosynthesis during the daytime.  Controlling idea:  Opening generally requires about one hour, and closing is often gradual throughout the afternoon.  Stomates close faster if plants are suddenly exposed to darkness.  The minimum light level for the opening of stomates in most plants is about 1/1000 to 1/30 of full sunlight, just enough to cause some net photosynthesis.  High irradiance levels cause wider stomatal apertures.
Third paragraph:  Topic sentence:  In most plants, low concentrations of CO2 in the leaves also cause stomates to open.  Controlling idea:  If CO2-free air is blown across leaves even in darkness, then their slightly open stomates open wider.  Conversely, high CO2 concentration in the leaves can cause the stomates to close partially, and this occurs in the light as well as the dark.  When the stomates are completely closed, which is unusual, external CO2-free air has no effect.  In short, stomates responds to intercellular CO2 levels but not to the CO2 concentration at the leaf surface and in the stomatal pore.  Succulents fix CO2 into organic acids at night, thus lowering internal CO2 concentration, which causes stomatal opening.
Fourth paragraph:  Topic sentence:  Stomatal of many species are highly sensitive to atmospheric humidity.  Controlling idea:  They close when the difference between the vapour content of the air and that of the intercellular spaces exceeds a critical level.  A large gradient tends to induce oscillations in opening and closing with a periodicity of about 30 minutes.  This is probably because, as the steep vapour gradient induces closing, CO2 in the leaf is depleted, and this in turn leads to opening.  The most rapid responses to lowered humidity occur under low irradiances.
Fifth paragraph:  Topic sentence:  The water potential within a leaf also has a powerful effect on stomatal opening and closing.  Controlling idea:  As water potential decreases (water stress increase), the stomates close.  This effect can override low CO2 levels and bright light.  Its protective value during drought is obvious.
Sixth paragraph:  Topic sentence:  High temperatures (30 to 35 oC) usually cause stomatal closing.  Controlling idea:  This might be an indirect response to water stress, or a rise in respiration rate might cause an increase in CO2 within the leaf.  High CO2 concentration in the leaf is probably the correct explanation for high temperature stomatal closing in some species because it can be prevented by flushing the leaf continuously with CO2-free air.  In some plants, however, high temperatures cause stomatal opening instead of closing.  This leads to increased transpiration, which removes heat from the leaf.
Seventh paragraph:  Conclusion:  It is clear that although many environmental factors are found to affect the opening and closing of stomates, CO2 is the key and the most direct factor in this phenomenon.  This information is important, particularly for those people who are doing research dealing with stomatal characteristics. 
(Source (with some modifications):  Salisbury, F.B. and C.W. Ross.  1992.  Plant Physiology (fourth edition).  Wadsworth Publishing Company. Belmont, California, p. 74-76).

As illustrated in the above example, the short essay consists of seven paragraphs.  The first paragraph contains the thesis sentence, while the second through to sixth paragraphs comprise the discussion which includes the five supports of the thesis sentence.  The seventh paragraph is the conclusion, which is a restatement of the thesis sentence.
In a longer essay (consisting of more than eight paragraphs), each part may be developed into two or more paragraphs.  In the above example, the title of the essay already suggest that the essay will not be extensive.  Therefore, each topic sentence can be just expanded into one paragraph.  In general, the relationship between the paragraphs containing the supports is direct and should be clearly shown in the working order of the sentences.

Students’ activity

Assignment 1

In the list below there are sentences expressing a position, belief, or point of view.  These sentences are intended to be thesis sentences.  However, they contain no proof, evidence, or reasoning to support a thesis.  In other words, they are vague and imprecise.  They do not give the essay any clear direction, besides there is no clear division between the subject and the supporting parts.  Your task is try to develop these sentences into thesis sentences with two or three supports.  Introduce the supports with words such as those in the examples already given.
1.  There is an urgent need for good extension services in the newly developed transmigration area in Jambi.
2.  The plant breeders and plant pathologists are found in every agricultural faculty in certain universities in Indonesia.
3.  Genetic engineering is a possible method to be applied in breeding pest and disease resistant plants.
4.  The rising cost of fertilizers and pesticides is a serious problem to horticultural industry in Indonesia.
5.  Vegetable growers in Pal Merah are facing very serious disease problems attacking their crops.

Assignment 2

Make an outline of a short essay based on the following title and thesis sentence.
Title                          :  The Difference between Dicotyledonous and Monocotyledonous Plants.
Thesis sentence   :  Based on botanical systematic, plants can be classified into two groups:  monocotyledonous and dicotyledonous.
Support 1                :  Monocotyledonous plants are characterized by …………
Support 2                :  Dicotyledonous plants are characterized by …………
Conclusion            :  It is clear that ……….
Upon have the outline, try to write a short essay consisting of four paragraphs.  The first paragraph consists of a short introduction leading to the thesis sentence.  The second paragraph develops the first support, the third paragraph develops the second support, and the fourth paragraph is the conclusion.

Vocabulary list

Agricultural graduate                  =  sarjana pertanian
Atmospheric humidity                 =  kelembaban udara
Botanical systematic                   =  sistematika botani
CO2-free air                                  =  udara bebas CO2
Critical level                                  =  level kritis
Dicotyledonous                           =  dikotil
Environmental factors                =  faktor-faktor lingkungan
Extension services                      =  layanan penyuluhan
Genetic engineering                   =  rekayasa genetika
Gradient                                        =  gradien
Grafting                                         =  penyambungan
Guard-cell                                     =  sel penjaga
Intercellular spaces                     =  rongga antar sel
Irradiance                                      =  iradiasi
Layerage                                       =  pencangkokan
Light intensity                              =  intensitas cahaya
Monocotyledonous                     =  monokotil
Nutrient deficiency                      =  defisiensi unsur hara
Photosynthesis                            =  fotosintesis
Physiological disorders              =  penyakit-penyakit fisiologis
Plant breeder                               =  pemulia tanaman
Plant pathologist                         =  pakar patologi tanaman
Respiration                                   =  respirasi
Respiration rate                           =  laju respirasi
Stem cutting                                 =  setek batang
Stomatal apertures                      =  bukaan stomata
Stomatal characteristics             =  karakteristik stomata
Stomates                                       =  stomata
Succulents                                   =  tanaman sukulen
Transmitted                                   =  ditransmisikan
Transpiration                                =  transpirasi
Unskilled farmers                        =  petani yang tidak terampil
Vapour content                            =  kandungan uap air
Water potential                             =  potensial air
Water stress                                  =  cekaman air

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