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13 WHAMPOA - An Interdisciplinary Journal 48(2005) 13-23

Lecture Comprehension in the CBT TOEFL Practice Book

Juei-ching Chung

Department of Foreign Languages, Chinese Military Academy, TaiwanLecture Comprehension in the CBT TOEFL Practice Book Abstract

The paper discusses the listening component, especially with regard to academic lectures,of two commercial TOEFL practice books published within the past five years. It examinesthe way the common course books reflect current defects in preparing students for the TOEFLtest in their treatment of the listening skill for the purpose of self-study or the TOEFL course.Based on the instructional implications of interactive models of listening, the paper presents athree-phase approach to adapting and supplementing a lecture selected from Lingua TOEFLComputer-Based Test (CBT) Listening Practice Test 1-4 . It implies that in order to help

learners to identify various aspects of lecture comprehension and gradually become efficientlisteners through their practice phase teachers who desire to improve their studentsperformance need to adapt and supplement listening tasks at the beginning of the instructionalphase.

Keywords: TOEFL, Lecture comprehension, Materials evaluation, Adapt, Supplement

1. Introduction

The Test of English as a ForeignLanguage (TOEFL) measures the ability of nonnative speakers of English to use andunderstand North American English as it isspoken, written, and heard in college anduniversity settings. In 1998, the TOEFL wasconverted from a paper-and-pencil test to acomputer-based test (CBT) format. The CBThas four sections: listening, structure,reading, and writing. The listening section iscomputer-adaptive, which means that thecomputer gives the participants testquestions that are aimed at their ability levels.Contents of lecture comprehension includeacademic seminars and discussions or academiclectures. The conversations are about 10 to15 lines long and may be between twostudents, a student and a professor, or astudent and a university administrator. Theseminars are longer, about two or threeminutes, and include dialogue by two to fivespeakers. The professor will do most of thetalking, with students also participating. Thelectures may be two different lengths, either

1 3 minutes long or 3 4 minutes long.During all of these exercises, listeners may

see diagrams, photos, or other visual aids.All questions are based on what is

stated or implied by the speakers. Amongfour sections, listening has been found to bethe most difficult part for test-takers becausethey can hear the material only once andcannot go back to the questions.Furthermore, listeners are not given theopportunity to see the listening input or totake notes while it is being played. Once theinput has finished, the question is heard andboth the question and response options aredisplayed on the screen. In addition totraditional multiple-choice items, the testincludes item types that ask test-takers toselect two options, to match or order objects,and to select a visual.

Principal materials currently available forthe TOEFL are primarily practice booksbecause the majority of them containexercises of the type contained in theTOEFL test. They cover several units of thetests, a listening script, and answer keys.Teachers need some things that are notcurrently provided in any TOEFL books,such as a comprehensive teachers manual

with useful teaching strategies, detailedanswer explanations, explicit language focus,

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examination tips, various types of unit testand topics, numerous practice tests, and anextension activity to develop more skills.Additional aids to listening includeproviding teachers with cassettes and CDs.

Some provides CD-ROMs, as well. Somecourse books, especially those published inthe United States, not only classify the testquestions into different categories accordingto strategies (e.g., idiom, key word,intonation, inference) or themes (e.g.,science, technology, art) but also providelanguage tips and background knowledge. Inorder to find out how far currently availablematerials meet the requirements of atest-taker and/or a teacher helping test-takers,two packages of test materials that arepopular and widely recommended byAmazon bookstore will be analyzed: LinguaTOEFL CBT Listening Practice Test 1-4 (LinguaForum 2001) and Deltas Key to theTOEFL CBT (Delta Publishing 1996).

While some TOEFL course booksmerely serve as a self-study practice booksor packages, others provide useful tips forteachers to arrange the course and evensuggest ideas to extend skill practice. LinguaTOEFL CBT is a practice book especiallydesigned for helping test-takers listeningcomprehension. Deltas Key to the TOEFLCBT can be a real coursebook for teachers toarrange a test-oriented course. If a book isaimed at providing test-takers with someunit practice, it should cover different typesof questions, genres, themes, and layouts of a lecture. If a book is designed for studentsindependent-study learning as well as to be a

teachers course guidebook, it shouldinclude teaching strategies to deal withtypical features of academic lectures. A goodlistening coursebook is crucial to teacherswho intend to help students prepare for theTOEFL listening test. This study willevaluate the usefulness and defects of thetwo books from the perspectives of atest-taker and a teacher preparing learnersfor the exam. It will also discuss howteachers adapt and supplement based on the

book in order to present listening strategiesin a more interactive way.

2. Literature review

2.1 Listening comprehension and

academic listeningIn accounting for the complex nature of

processing spoken language, it has beenhypothesized that bottom-up andtop-down modes work together in acombined cooperative process[15]. Listenershear the spoken text according to their ownpurposes for listening, their expectations,and their own store of backgroundknowledge. Brown and Yule[3] suggestdividing language functions into two majordivisions: language for interactionalpurposes and language for transactionalpurposes. A model of materials designed forsecond-language listening comprehension shouldcombine these language functions(interactional and transactional) andlanguage processes (top-down andbottom-up). In the situation of a listeningcomprehension test such as TOEFL,listeners usually have to deal withtransactional information in order toconstruct old or new concepts. Listenersmay have had the prior knowledge, but theyhave to match the stream of sound heldbriefly in the short-term memory withinformation from the long-term memory inorder to elaborate upon and verify theinterpretation of the input. In addition, theyhave to respond in time and within ananxious test situation.

Strategies presented for listeners should

be oriented toward discovering theunderlying structure and argument of alecture. Specifically, they should illustratenonnative listeners variable success inrecognizing the main points of a lecture asderived from their following eitherpoint-driven (i.e., problem-solution) orinformation-driven (i.e., description andrelational presentations) strategies in listening.A mismatch of strategy with lecturestructure can lead to serious

miscomprehension of main points. It isessential for teachers to determine those

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Juei-ching Chung: Lecture Comprehension in the CBT TOEFL Practice Book 15

lecturing and listening strategies that aremost effective for comprehension andretention. Most common issues concerninghow teachers help students in preparing forthe listening comprehension test include

speech rate, vocabulary elaboration,discourse markers/rhetorical structure, andbackground knowledge. Among all,discourse markers and rhetorical structureattract researchers attention for theirinherent usefulness in making the structureof the discourse understandable and aspotential aids in training listeners tocomprehend better [4][9][13][14][18][19].

Instruction has a sound basis inpresenting and evaluating sample lecturesthat illustrate the forms and variablefunctions of the features of academiclectures [8][9][13]. They include: (1) globalmacro-organizers; (2) local macro-organizers;(3)move types; (4)transaction types andsequence structure; (5) asides; (6) definitions;(7) vocabulary elaborations. Certain lexicalphrases or rhetorical markers definitely helpsignal the major content and sequence in anargument and demarcate the boundaries of nonessential information. Making learnersmore aware of the structure of the discourseshould improve their ability to processlecturesto predict, identify, and associatemeanings and references both within andoutside the lectures.

2.2 Criteria for materials evaluationBecause the TOEFL practice book or

package is based on the TOEFL test,question types tend to be the focus of the

material designers. Most practice booksexplain the reasons for the answer based onthe question. Questions based on lecturecomprehension usually cover identificationof the purpose and scope of a lecture,recognition of key lexical items related to atopic, and familiarity with different styles of lecturing [17]. Among the nine mostimportant listening activities as identified byuniversity lecturers in the Powers survey[16], six seem to affect the question types of

the TOEFL listening test:1. Identifying major themes or ideas of

lectures2. Identifying relationships (e.g., order or

cause and effect ) among major ideas ina lecture

3. Identifying the topic of the lecture

4. Inferring relationships betweenconcepts contained in the lecture5. Comprehending key information

presented in the lecture6. Identifying supporting ideas and

examples in the lecture.In Richards taxonomy, the lecturers

rated as most important for academicsuccess are those activities that address alisteners understanding of the main pointsand supporting details of a lecture. Insteadof taking notes using a pen, listeners have totry to remember all they can and take notesin their head. The first question is usuallyabout the general topic, main idea, orpurpose of the discussion or lecture. Theywill have to get a sense of the topic in thefirst few sentences. Sometimes, the TOEFLpeople will try to trick listenersthe lecturemay begin with a reference to a past lectureor something else. Answers that are too

general or too specific are included in orderto test listeners overall comprehension.Some TOEFL practice books give reasonsfor the incorrect choice rather than simplytrying to convince listeners withexplanations of the correct choice. Thisleads test-takers to search the wrong answersfirst in order to avoid the tricks. Fewpractice books mention the structure of thespeech or point out the discourse markersand rhetorical structure. As a result, those

learners who study the TOEFL test on theirown do not benefit much from the books.

Currently, there is no commercial coursebook available in the market for teacherstrying to help students prepare for theTOEFL test. Therefore, it seems that theprincipal TOEFL-oriented books can beevaluated from the most useful part of thebookhow accessible is the informationor explanations provided by the AnswerKey? Do readers really understand theexplanations of the correct choices? Is thereany ambiguity in the explanations? How

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convincing are the explanations? Are readersclear about what they are supposed to betested on and answer? How do teachersadapt or supplement a lecture in order tohelp test-takers reasonably interpret the

speakers intention and infer the meaning inthe sequence of the argument?

2.3 RecognitionFor pedagogical purposes, it is useful to

focus on two major language functions:language for transactional purposes andlanguage for interactional purposes, as in thecase of the TOEFL test. It is important formaterial designers to take into account thenature of listening and informationprocessing as framed in a top-down andbottom-up conceptualization. Tasks of top-down processing are aimed at helpinglisteners evoke their prior knowledge andglobal expectations about both language andthe world. Here, listeners bring their knownlanguage to bear on the task of understanding the incoming stream of speech. This allows listeners to predicton the basis of context (both thepreceding linguistic context and thesituation-and-topic, setting-and-participants context)what the incoming message at any point canbe expected to mean and how it fits into thewhole.

On the other hand, tasks of bottom-upprocessing enable listeners to understandincoming language that is worked outproceeding from sounds, to words, togrammatical relationships and lexicalmeanings, and finally to a composite

meaning of the message based on theincoming language data[11]. Therefore,tasks or activities are especially useful earlyin the semester, especially if they aredesigned with a focus on introducingstudents to learning goals such as languagecompetence, listening strategies, and criticalthinking. Through the activities, teachersintroduce concepts with any eye towardhelping learners develop self-awareness andself-consciousness.

Models of listening instruction have beenwidely developed over the past decades and

have been integrated into materials design.Designers of the materials dealing withacademic skills, especially reading and writing,offer step-by-step activities that help learnerscomprehend the text or generate ideas.

However, academic listening materials havebeen rarely seen partly because they need ahigh level of academic (EAP) andpre-professional/professional (EPP) facilitywith English rather than only general Englishskills. Lecture comprehension covers differentfields, mostly about important issues present inthe campus culture, on aspects of Americanculture, and on social, economic, and politicalissues of general interest and concern in bothinternational and national arenas.

As to the test situation, the main goal of academic listening here is to comprehendthe speech and be able to choose the correctanswer. By and large this kind of materialfeatures a student response pattern based ona listening-and-question-answering modelwith occasional innovative variations on thistheme. No matter how well done, this kindof listening instruction represents only asmall promportion of unidirectionalnon-interactive (i.e., one-way) listening.Such listening programs are not sufficient tothe task of developing functionallycompetent listening skills[12]. Teachersshould adapt and supplement materials toencourage students linguistic development,critical listening, and critical thinking. If thespoken text represents a heavy load of information, simplification of the text mightaid comprehension. Simplification is aprocedure designed to make things easier for

or more accessible to the learner by meansof editing of texts to reduce linguistic orconceptual difficulty [10]. Ideally, thelanguage classroom should help students todevelop listening processes in a systematicway through activities in which linguisticinformation, contextual clues, and priorknowledge interact.

3. Evaluation of the materials

Although researchers have addressedthe importance of two major

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Juei-ching Chung: Lecture Comprehension in the CBT TOEFL Practice Book 17

strategiestop-down and bottom-upprocessing of information[5][21][20]course books or course packages forpreparing for the TOEFL test have beenrarely centered on developing test-takers

listening strategies. For example, DeltasKey to the TOEFL Test arranges each unitsimilar to the real test by providing sometest skills such as helping listeners identifythe topic and main ideas, comprehendingdetails, matching words and categories,sequencing event in a process, determiningreasons, making inferences and predictions.Most of the commercial TOEFL listeningpractice test books are essentially practiceand are not designed to assist teachers inhelping test-takers or to help test-takers toreally solve their listening problems.

Most TOEFL listening books including Lingua TOEFL CBT , are merely designedfor test-takers self-study. Lingua TOEFLCBT consists of four actual TOEFL-likelistening practice tests with answerexplanations added. Often it explains themain topic or comprehension question byeliminating the other incorrect answerswithout analyzing the real feature of alecture. If the critical information that givesclues to the test questions is printed in boldor colorful type, the listening script willdefinitely help self test-preparers grasp theoverall structure of the spoken text andindicate major sections. This feature of thelistening script will get students familiarizedthemselves with a variety of lectures anddevelop their ability to identify majorthemes, ideas, key information, supporting

statements, and examples in the lecture. Bypointing out discourse markers in italics, thelistening script can help self test-takers tobecome aware of the major content andsequence in an argument, and todiscriminate essential from nonessentialinformation. It is important that materialsdevelopment take principles of studentsindependent learning into account.

Major TOEFL course books currentlysold on the market today exclusively focus

on exercises or practices of test questionsaccompanied by listening scripts. Few of

them incorporate listening activities throughwhich learners can develop listening skillsand strategies for lectures. Until recently,some course books, such as Deltas Key tothe TOEFL Test , have contained test-type

questions in exercises, quizzes, and tests;annotated answer keys and explanations thatrefer to units of study; descriptions of newcomputer-unique test items; convenientorganization and thorough cross-referencingof skills; suggestions for student-centeredpair and group activities, games, and oralpresentations; and peer reviews.

However, as lecture comprehension isscripted and linguistically academic, it isdifficult and cognitively demanding forthose students who have never experiencedthe TOEFL test to comprehend. In order tohelp test-preparers quickly familiarizethemselves with the TOEFL test, Deltas Keyhas analyzed question types, categorizedthem, clearly described each type, and notedthe proportion in which each appears on thetest. They have also suggested strategies forthe test in general and for each type of question in particular. They have includeddiscussion of trick questions and havebuilt on the philosophy that listening skillbuilding and assessment are interrelated.Overall, their course addresses the specificlanguage skills necessary for success on theTOEFL and in university studies.

However, if a practice book like DeltasKey to the TOEFL Test also features itself asa course, it should incorporate tasks to buildtwo things: (1) a base of content experiencesthat helps to develop expectancies and,

gradually, a repertoire of familiar top-downnetworks of background knowledge; and (2)a base of outcome experiences that helps tobuild a repertoire of familiarinformation-handling operations in lecturesthat are applicable to similar context.Therefore, tasks give students opportunitiesto analyze selected aspects of both languagestructure and discourse markers and todevelop some personal strategies to facilitatelearning are important, especially at the

beginning of the skill-training stage[15].

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Juei-ching Chung: Lecture Comprehension in the CBT TOEFL Practice Book 19

are definitely necessary so that teachers canprepare their specific students.

Teachers should first understand thecourse itself very well and their studentsweaknesses in coping with lecture

comprehension. The materials teacherschoose for the course should be flexibleenough to supplement any task that enableslearners to activate their prior knowledgeand develop both bottom-up and top-downprocessing and reasoning skills.

Overall, the two TOEFL listeningpractice books mentioned in this paper arefriendly and pleasing course books. There isa variety of practice exam tasks, and theanswer key provides useful strategy andexamination hints (together withexplanations and tips). There is an attempt tobe teacher friendly in Deltas Key to theTOEFL Test , with a selection of tapescriptsat the back of the book, and a page devotedto each tapescript. For teachers, the coursebooks serve as a starting point. What is moreimportant is being able to select a text theperceived flaws of which are correctable, inthe sense that the teacher can easily makethe authors biases more harmonious withhis or her own[1] and more appropriate tohis or her students proficiency levels andlearning goals.

This paper has evaluated the usefulnessand defects of the two leading TOEFLpractice books from the perspectives of atest-preparer and teachers preparing learnersfor the exam. It also gives an example of adapting a test unit, supplementing listeningtasks, and rearrangement of test questions. It

is hoped that lecture comprehension will beachieved to some extent by getting thestudents to predict what the answers might be,by encouraging them to listen selectively, andby adapting the script into a more authenticspoken lecture with more oral features(possibly using a native speaker to deliver orrecord the adapted version). However,teachers should go back to review the lecturein its original version because students areexposed to it and are tested on it.

References

[1] Ariew, R., The textbook as curriculum. InT.V. Higgns, (Ed.), Curriculum,competence, and the foreign language

teacher ,Skokie, IL: National Textbook Co,pp. 11-33(1982).

[2] Celce-Murica, M., Teaching English as asecond or foreign language, Boston:Heinle & Heinle Publishers, pp.86-88(1991).

[3] Brown, G.., & Yule, G.., Teaching thespoken language , Cambridge:Cambridge University Press(1983).

[4] DeCarrico, J., & Nattinger, J. R.,Lexical phrases for the comprehension of academic lectures, English for SpecificPurposes, Vol. 7(2), pp. 91-102(1988).

[5] Dijk, T., & Kintsch, W., Strategies of discourse comprehension, New York:Academic Press(1983).

[6] Hansen, D., & Jensen, J., Evaluatinglecture comprehension. In J. Flowerdew,(Ed.), Academic listening: Research

perspectives, Cambridge: CambridgeUniversity Press, pp. 241-268(1994).

[7] Hutchinson, T., & Waters, A., English for specific purpose: A learning-centered approach , Cambridge: CambridgeUniversity Press, pp. 97(1987).

[8] Lebauer, R.,Using lecture transcripts inEAP lecture comprehension courses,TESOL Quarterly, Vol. 18(1), pp. 4154(1984).

[9] Lebauer, R., A syllabus for an advanced ESLlecture comprehension and note-takingcourse, Occasional Paper 6 ,

Department of ESL, Honolulu,HI(1985).[10] McGrath, I., Materials evaluation and

design for language teaching, Edinburgh: Edinburgh UniversityPress(2002).

[11] Morley, J., Listening comprehension insecond/foreign language instruction, In M.Celce-Murica (Ed.) Teaching Englishas a second or foreign language, Boston: Heinle & Heinle Publishers, pp.

81-106(1991).[12] Morley, J., Academic listening

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comprehension instruction: Models,principles, and practices, In J.Mendelsohn & Rubin, J., (Eds.), Aguide for the teaching of second language listening , Los Angeles:

Dominie Press, Inc, pp. 186-221(1995).[13] Nattinger, J., & DeCarrico, J., Lexical

phrases and language teaching , Oxford:Oxford University Press(1992).

[14] Olsen, L. & Huckin, T., Point-drivenunderstanding in engineering lecturecomprehension, English for SpecificPurposes, Vol. 9(1), pp. 33 -47(1990).

[15] Peterson, P., A synthesis of methods forinteractive listening, InM.Celce-Murica (Ed.) Teaching

English as a second or foreignlanguage, Boston: Heinle & HeinlePublishers, pp. 106-122(1991).

[16] Powers, D., Academic demands related tolistening skills, Language Testing, Vol.3(1), pp. 1 -38(1986).

[17] Richards, J., Listening comprehension:Approach, design, procedure, TESOLQuarterly, Vol. 17(2), pp.219 -2 40(1983).

[18] Rounds, P., Characterizing successfulclassroom discourse for NNS teachingassistant training, TESOL Quarterly, Vol.21(4), pp. 643-671(1987).

[19] Shaw, P., The language of engineeringprofessors: A discourse and registralanalysis of a speech event, UnpublishedPh.D. dissertation. University of Southern California(1983).

[20] Shohamy, E., & Inbar, O., Constructvalidation of listening comprehension

tests: The effect of text and questiontype, ERIC Doc. No. ED296594(1988).

[21] Voss, B., Slips of the ear, Investigationsinto the speech perception behavior of German speakers of English , Tubingen,Germany: Narr(1984).

Appendix

A. Teaching approach:

(I) Pre-listening phasePre-listening task (given by a native speaker

during the first hour of the class):Topic: What do you think the lecture is about?Lexical Items: Look at the following wordsand discuss the meaning with yourclassmates.

(a) silver chloride(b) prism(c) radiation(d) ultraviolet (UV) radiation(e) quartz tube(f) UV light (blacklight)(g) ergosterol(h) (f) fluorescence

Pronunciation:(1) Check to see if you can correctlypronounce the lexical items listed above.(2) Have you ever heard about the followingpeople? All of them have something to dowith the items listed. Listen to your teacherpronounce the names and make sure you canidentify the sounds.

(a) Johann Wilhem Ritter(b) Peter Cooper Hewitt(c) David Olivetti

(II) While-listening phase

Activity while listening (given by anative speaker during the first hour of theclass):

Stage 1Your teacher will explain various

phenomena of ultraviolet radiation in thislecture. You will have to organize thefollowing in chronological order:

(a) Why scientists named the radiationultraviolet.

(b) How ultraviolet light is applied to (usedin) photography

(c) How blacklight can be created(d) The experiments of physicist Johann

Ritter with prisms and silver chloride .

Stage 2When you listen to your teacher present

these well-known events in physics, watchout for the names connected with each eventor phenomenon. Now, articulate the namesagain in your mind and listen to your teacher

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Juei-ching Chung: Lecture Comprehension in the CBT TOEFL Practice Book 21

giving a lecture about ultraviolet radiation(see the adapted version in Appendix C).Check your understanding from time to timewhile hearing. Feel free to interrupt yourteacher if you do not understand.

Stage 3Ultraviolet (UV) light will now be

applied in daily life. Pay special attention tothe content or object connected with thepresent.

Stage 4Now, you may have grasped the scope

of the lecture your teacher has given. Whatis the topic of the lecture?

(a) The life of Johann Ritter(b) Silver chloride(c) Types of radiation(d) The uses of ultraviolet radiation

(III) Post-listening phase

Post-listening Task (discussed instudents mother tongue during the secondhour):

Your teacher will play a recording or

the whole lecture (Appendix A). Discuss thesimilarities with and differences from theauthentic lecture presented by the previousteacher. Write down the difficult parts or theproblems you encounter in the process of authentic and recorded lecturecomprehension, respectively. Discuss theproblems with your peers.

B. The Original Version:

InstructionsListen to the following recorded talk,

and then answer the multiple-choicequestions below.

The Listening Text

In 1801, a German physicist named (1)2.1,3.1Johann Wilhem Ritter experimented with silver chloride and a prism . He passeda beam of sunlight through a prism, whichdivided the beam into the colors of thespectrum. He then placed some chloride in

each color to see what would happen. Thered caused little change. Deep violet,however, made the bits of chloride darken.Then Ritter tried some chloride in thelightless space just beyond the violet. The

material grew much darker, almost asthough it were being covered with soot. Hehad discovered a powerful, invisibleradiation beyond the violet in the suns colorspectrum.

2.2Scientists named this radiationultraviolet, meaning beyond violetlight. They found that it traveled in waveslike light and at the same speed. It differedhowever, in having shorter wavelengths anda higher frequencythat is, more waves persecondand in fact it was invisible to thehuman eye.

For a century, scientists used ultravioletradiation from sunlight, electric sparks, orelectric arcs. In 1901, (2) 3.2 Peter CooperHewitt of New York City 2.3 made a muchmore powerful source by passing an electriccurrent through a quartz tube filled withmercury vapor, called the UV light orblacklight.

In the 1950s, (3) 3.3 David Olivettidiscovered that ultraviolet rays producevitamin D in the body. The radiation acts ona fatty substance under the skin, calledergosterol, and changes it to vitamin D.Today, many foods contain man-madevitamin D.

4.1Ultraviolet radiation has also proved to be a powerful germ killer , andmost meats sold today in America have beenirradiated to kill germs. 4.2Ultraviolet lights

are also used in hospitals to keep air sterile .More recently, 2.4 photographers havelearned how to use ultraviolet light to takepictures in the dark, and detectives can usethe glow that ultraviolet light causessubstances to give off, called fluorescence,to detect forged documents, fingerprints, andother clues.

Not all of ultraviolet lights effects arepositive, however. UV rays are also responsiblefor tanning and burning the skin, which can lead

to cancer, so care must be taken on sunny daysto protect oneself from them.

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The Questions

1. What is the main topic of this lecture?a. Types of radiationb. The life of Johann Ritterc. The uses of ultraviolet radiationd. Silver chloride

2. The professor explained variousphenomena of ultraviolet radiation inthis lecture. Put these events intochronological order.

Click on a sentence. Then click onthe space where it belongs. Use eachsentence only once.

The word Ultraviolet is coined.Ultraviolet light is applied to photography.The black light is invented.

Johann Ritter experiments with prisms & silverchloride.

(1) (3)

(2) (4)

3. Physicists have invented many kinds of things. Match the person with hisdiscovery.

Click on a name. Then click on thespace where it belongs. Use eachname only once.

Johann RitterPeter HewittDavid Olivetti

Discovered thatUV rays can

create vitamin D.

Discoveredultraviolet rays.

Created theultraviolet lamp.

4. How is ultraviolet light applied ineveryday life?

Click on 2 answers.

A To kill germs in meat.

B To improve fuel efficiency.

C To produce ergosterol.

D To keep air sterile in hospitals.

B. Adapted LectureLet us begin by considering the history

of technology and science. The things weknow today, even the things that arecommon knowledge today, were not always

known. Indeed, many of the scientific andtechnological advances that have greatlybenefited societythings that we more orless take for grantedwere discovered anddeveloped only through painstaking research,experimentation, and, yes, trial and error.

Here is an example. There was a timewhen the electromagnetic spectrum was amystery. Even when scientists began tounderstand light there was no understandingof wavelengths beyond the visible-lightspectrum.

This started to change in 1801, when aGerman physicist named Johann WilhelmRitter experimented with a prism and thecompound silver chloride. Initially, hepassed a beam of sunlight through a prism,which divided the beam into the colors of the visible-light spectrum. Next, he placedsome chloride in the beam of each color, justto see what might happen. He found that thered beam caused little change but that thedeep violet beam made the chloride darken.Then came the great breakthroughheplaced some chloride in the lightless space

just beyond the violet. The material grewmuch darker, almost as though it were beingcovered with soot. What Ritter haddiscovered was a powerful, invisible form of radiation beyond the violet in the Sunscolor spectrum!

This new radiation was called

ultraviolet, meaning beyond violet.Scientists soon found that it traveled inwavesjust like visible lightand at thesame speed. However, it differed fromvisible light in that it had a shorterwavelength and a higher frequency (morewaves per second) and in the fact that it wasinvisible to humans.

For the next century, scientistsexperimented with ultraviolet radiationusing sunlight, electric sparks, and electric

arcs. Then, in 1901, the American scientistPeter Cooper Hewitt of New York created a

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Juei-ching Chung: Lecture Comprehension in the CBT TOEFL Practice Book 23

much more powerful source by passing anelectric current through a quartz tube filledwith mercury vapor, which he called theUV light or blacklight.

Still, this amazing scientific discovery

had produced no practical benefits. Finally,in the 1950s, David Olivetti found thatultraviolet rays produce vitamin D in thebody. The radiation acts on a fatty substanceunder the skin, called ergosterol, andchanges it to vitamin D. Today, many foodscontain man-made vitamin D.

So, lets look at this. It took 150 yearsfor this startling discoverythat there werewavelengths of electromagnetic radiationbeyond the visible spectrumto result inany practical benefits. In the end, however,the discovery of UV light would prove to bevery valuable to society.

In addition to producing vitamin D, itwas found that UV radiation was a powerfulgerm killer, and today most meats are

irradiated with UV to kill germs. Ultravioletlights are also used in hospitals to keep airsterile, and more recently photographershave used ultraviolet light to take pictures inthe dark. Law enforcement officials even use

UV to discover forged documents,fingerprints, and other clues.

Along with these benefits, however, ithas been found that UV can have negativeeffects, as well. We now know thatultraviolet light is responsible fortanningand burningof the skin, whichcan lead to cancer. Thus, we have to takeUV seriously in order to protect ourselves onsunny days. We can do this by usingointments that prevent the UV radiationfrom damaging the skin.

This is a good example of how aprimary discovery in physics has resulted inbenefits to society and enlarged ourknowledge in other areas, such as theprevention of skin cancer.

LinguaTOEFL Computer-Based Test (CBT) Listening Practice Test 1-4 Deltas Key to theTOEFL CBT

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