High School Chemistry Textbooks: Form and Function - A SYMPOSIUM

What High School Chemistry Texts Do Well and What They Do Poorly Dorothy L. Gabel Science Education, Indiana University, Bloomington, IN 47405

Chemistrv teachers freauentlv ask the guestion, "Whv do so many hiih school chemistry students have difficulty with chemistrv?" Manv students feel iust like Lucv in the cartoon when she says, "i was going along real g o d when all of a sudden I pulled a muscle in my head." Some chemistry stu- dents appear to pull a muscle by the end of the first week in class, and it happens to many more a t the time that they study the mole concept! Chemistry textbooks should be examined from the student's point of view. After all, the textbooks are purchased for and by students, not teachers. Do chemistry textbooks facilitate learning? Do they contain muscle relaxers that help students learn chemistry?

Cluster Goals There are several basic assumptions that chemists and

chemical educators make about what chemical education should accomplish. Some of these assumptions are that

1. Students should understand the nature of the scientific enter- prise.

2. Students should have a sense of what chemists do. Career edu- cation is an important educational objective.

3. Students should be familiar with the "matter" that surrounds them. How many students think that chemistry deals exclusively with mysterious powders and liquids in jars in the chemical storeroom?

4. Students should be able to sort out sensible statements from

These basic assumptions correspond to what the National Science Teachers Association advocates as the cluster of goals for Project Synthesis (1). Project Synthesis was acompilation of three NSF and NIE national studies of the status of science education in the 70's. The four area goals formulated in Project Synthesis were societal issues, career education, salient knowledge. and uersonal needs. Analvses of all four sources of ~rojec; synthesis indicated that thescience textbook exerts an overwhelming dominance over the science learning expe- rience. This makes it imperative that these four cluster goals be reflected in chemistry texts. Data from one source indicated that 90-94% of 12,000 (science) teachers surveyed used the text 90% of the time (2).

When chemistry texts are surveyed, however, it is rarely found that all four of these assumptions are reflected in a single chemistry text or program. In reality, some texts do a poor job a t incorporating more than one of them. One text that was exemplary in including the first two assumptions hut neglected the other two was never the success that it should have been. In the preface of the hook, it is stated:

A clear and valid picture of the steps by which scientists proceed is carefully presented and repeatedly used. Observation and mea- surements lead to the develoornent of unifvina principles and then . .. these principles are used lo interrelate diverse phenomena. Heavy

Presented at the 7th Biennial Conference on Chemical Education in Stillwater. OK, August 12, 1982. Symposium-High School Chem- istry Texts: Form and Function.

reliance is placed upon laboratory work so that chemical principles can be drawn directly from student experience. Not only does this give a correct and nonauthoritarian view of the oriein of chemical urinci-

experiment and theory. Chemistry is gradually and logically unfolded, not presented as a

collection of facts, dicta, and dogma (3).

Successive Editions The above atatcmrnts wrre takvn frum the or:ginal CHEM

Study Text. Since the p l ~ l i c a t i m of the CHKM Study trxt in l ! I f i4 , other t.htmistry texts haw undergone major rhangw. Huwver, instead of focusing on [he approach that ('HEM Study endorses, other textbook pul~liahers addrd additionnl contt:nt that was included in the CH KM Study text. 111(11'cd, what CHEM Study espousrd was lrs-. ob\ i(n~i!

TU illustrilte, the change.: that h:>w occurrvd mer a 2tl-year span in sucressive editicms of th t hvit selling chemistry text, "Mlldern Chemistry" ( 4 ) , have been exa~ninrd. They are t.ypical of changes that have occurred in other texL5 during this same time prri<,d. Modit:cations tn:lr occtlnd l n m 1!J5.> to 19-A in the rl~aoters on atomic theor\.. the i~rri<,dic law. m d bonding illustrate the point (see tahiej.

In 1958, the chapter on atomic structure explained atoms in terms of Bohr's theory, KLMN shells, and electron dots. Bondine was discussed orimarilv in terms of valence with electrodots used to show how electrons were exchanged and stored. The chauter on the oeriodic law was mainlv descrip- tive.

Development of Science Content in "Modern Chemistry," 1958-1978

Atomic Structure Bonding Periodic Law

1985 Bahr Theory Ionic and Covalent Descriptive KLMN Shells Bonds Electron Dots Electron Dots

Valence 1962 s p d f Diagrams More Reference to Periodicity With

Bonds Ionization Less Reference to Energy

Valence 1966 Describes Orbitals In Terms of Orbitals Electron Affinity

Electron Configuration Notation

1974 Expanded to 2 Energy Change Chapters Oxidation-Reduction

Rutherford's Resonance Experiment Hybridization

Avagadro's Number and Mole

1978 G-eater Emphasis on Hybridization Mole Expanded

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Over a 20-year span, these chapters became more theoret- ical and mathematical in nature. Very little material from previous editions was deleted and much more material was added such a s s p d f orbital configuration notation and di- agram, ionization energy, and electron affinity. By 1974, the chapter on atomic structure had expanded to two chapters. Avogadro's numher was added to the atomic theory chapter. Redox, resonance hybridization, and energy were changed to the chapter on bonding. These additions are typical of changes other puhlishers were making in their chemistry texts also.

In order to accommodate this extra material, the publisher has three choices. The textbook can he expanded, other ma- terial can he deleted. or existine material can he condensed. From a student's point of view h e r e are prohlems with each. In an attemnt to undate the textbook. somethine for which puhlishers should be commended, there are inherent proh- lems.

Each of these possihilities must be considered in terms of the students learning chemistry. Over the years chemistry has always been a difficult subject for students to master. It fre- quently seems fragmented and makes little sense. This was true in 1958 and probably 1938. The questions that must he asked are, Are students in 1982 different from those in the

iutswered i n the ncydi\v. S tudp~~ts ' ici~oa.e hnckpound i nl) hmer Studcnr~ tudii\. ipenil mtre rime m.nmli:htin: and art. not as motivated as their early 60's counterparts of the "Suutnik era."

The mental capacity of students has also not significantly increased within the past two decades. When new material is added to the chemistry textbooks and other material is not deleted, can we expect students to learn all the material? This question is pa~ticularly appropriate when students have less time than before to study. Yet, puhlishers include all of this material between the two covers of the text and even include such statements as: "It has been the authors' purpose to in- clude more material than can he covered in one vear, thus permitting a wide choice of topics and allowing fo; selective emphasis. Teachers should feel free to choose those topics which best meet their needs" ( 5 ) . Teachers, however, do not feel free to choose. I t is difficult for them to know which to~ ics are prerequisites for others in the concept development of a eiven text or which touics thev must cover to meet the ex- "

pectations of chemistry professors of freshman college chemistry courses. This prohlem will become more prominent because textbooks play an even greater role in the teaching of chemistrv as less-aualified teachers replace hirhlv com- petent retiring chemikry teachers in the current chemistry teacher shortaee.

Instead of expanding the textbook, puhlishers frequently delete material or condense it to maintain approximately the same number of pages and to keep costs~down. "Modern Chemistry," for example, has actually decreased in length from 661 pages in its 1958 edition to 628 pages in its 1978 edition, although some of this may be related to changes in format and textbook size. In the 1958 edition 326 pages were given to theoretical chemistry including organic chemistry. In the 1978 edition, this had expanded to 463 pages, an in- crease of approximately 40%. This constitutes the first 463 napes of the hook. those nazes which the student is most likelv toencounter if the teaclkxpresents the material in the order given in the text. As noted earlier, many of these additions are mathematical and abstract in nature, requiring more time to learn than the descri~tive chemistrv for which it was substi- tuted. Because students spend moretime studying theoretical chemistrv. less time is soent on descriutive chemistrv-the . . wry asp(.cr\ oi(l~emisrry that h d p sttt(lrnts undtntand the w d d arrmnd them and mskt chetniqy ~~rnctit.rl 1)). rilkmg

into account their personal and societal needs. The goals that chemistry educators set in this area are never met because of the location of the descriptive material in the text.

If the textbook publisher chooses to limit the size of the hook by condensing the material, the textbook becomes quite useless to the student as a learning tool. Treatment of the topics becomes so superficial t h a t students memorize the vocabulary instead of learning the concept. Density is a case in point. In some high school chemistry textbooks, the authors assume that students understand the meaning of this complex concept; no introduction is given to the term whatsoever. I t is never defined but just used like the word "volume" or "mass."In "Modern Chemistrv." the 1974 edition nresented the concept using a series of five pictures showing the masses of eaual volumes of five substances. The formula was ziven with'two brief examples. In the 1978 edition, the five pictures were replaced with one picture, that of one liter of water. The formula was given with instructions on how density is exper- imentally obtained. Neither approach provides the student with adequate instruction for understanding the concept of densitv. A combination of these two, which would have taken up mire space in the textbook, probably would have been better.

Another way to condense the content of a textbook is to present concepts quantitatively using formulas without giving an adequate qualitative introduction to the concept. For ex- ample, when molarity is presented first as the formula M = moles of solutelliters of solution, students perceive molarity as a formula to be used rather than a condition in which

meaning of molaritv within two weeks after the concent had been taight (6). ~ e k u l t s of the study showed that 35%of the students were able to zive a definition of molaritv without "

prompting, whereas only 17% could descrihe how to make up one liter of a 2 M sodium chloride solution. Yet 30% could work a simple molarity problem and get the correct answer!

Memorization Versus Understanding Examination of textbooks shows inadequate qualitative

introductions to many concepts such as the gas laws, molar volume, and pH. The result of the inadequate qualitative in- troduction alone with the increase in content that students are expected to ihsorh is that students memorize the concepts instead of understandine them. Thev are therefore unable to - make connections between concepts, and chemistry becomes fraemented and imoossihle to learn.

&her features df textbooks that lead to memorization rather than to the understandinr of conceuts include the following:

1. Presenting problem-solving using sample problems based on aleorithms and formulas rather than on reasoning. When several crsnlplcs nrr prr.wn1t.J. .:llrlcnl- 1.ml t . nwm r r v r thr .:trnplc pruhlcm~ d d 111,,!1 I < \ 1 , !n?tc h lh t lr pr,hl,.rn \ \ i l l > Ihc me181 m,cd A.rt.ritl>~l> r:~tlwr I I M U R~WIIIII: cut 1111 U I . 11 ' I ' r>u . d i l ~ m , the whole purpose of assigning problems to get students to understand the concepts better. The number and placement of sample problems in textbooks also needs careful examination.

2. The introduction of complex mathematical processes that stu- dents do not understand such as the use of logarithms in solving pH problems. Students are forced to memorize the algorithm because they do not understand the meaning of the logarithm. This reinforces the idea that problems are best solved by memorizing procedures.

3. The introduction of diagrams that are not helpful far learning the concept because the diagrams are complex and difficult to un- derstand. Titration curves are an example of this.

4. The introduction of superfluous concepts. Is it necessary to in- troduce molarity, molality, and normality in high school chem- istry?

5. Presenting concepts with no basis in experimentation such as introducing moles in atomic theory and redox reactions in bonding.

894 Journal of Chemical Education

6 Presenting elaborate theoretical models a$ estahlished facts. This happens when theory is presented before students have factfi that need explanation, such as introducing atomic structure, electron configuratmn, and chemical bonding before the Laws of Definite Camposltion and Multiple Proportions, and balancmg equations.

Better Understanding of Chemistry

The title of this paper is "What High SchoolTexts Do Well and Do Poorly." There are some things that high school texts do well and for which publishers must he commended. Books are frequently revised to include updated, scientifically correct information. Learning aids such as glossaries, tables, high- lighting, and pronunciation guides have been included. Pic- tures and diagrams have become clearer and an attempt has been made to control the readability of texts. These are im- portant adjuncts that lead to the better understanding of chemistry.

As to the things that are done poorly, chemistry teachers must ask themselves if they want textbooks to improve. Is there consensus among teachers as to the direction of the changes? NSTA has put forth four cluster goals: societal

needs. versonal needs. career education, and salient knowl- edge. 1s there agreement that these should he reflected in the chemistry textbooks of the 80's and 90's? Publishers print what the market demands. Teachers must remember that they control the market in that they select the texts that are used by their students. If chemistry teachers continue to demand that texts include all there is to know about chemistry, there is little hope for any improvement in the future. Twenty years from now, Lucy will still be using that pulled muscle in her head as an alibi for not understanding chemistry!

Literature Cited ti,., ...,, . 9 " > K , , T . , r,.. I,, ,..'<..,",.. I.:, .. st,: ,,,.? " m l l ' r

.,I ,,..,' I , . . , . . . , . l . ... ' , ,< I . . T . : , 7 ,<.I., I?*,. <, ,L I. k' s d k . I,\ I ., ,. .. I. . .. . kl.:,', , '' 'c",*c' . I#> . , I , . 8 , I . 1 . 8 . k...#ja1 1 1.1 n . . I1 .I$-*.I 1h.plirII.I.

(3) Chemistry An Expezimentsl Science." 1st Ed.. W. H. Froeman and company, San Francisco, 1963, pp. vii-viii.

(4) Metcslfe, H. Clark, et al., "Modern Chemistry: Hdt , Riniart and Winston. Inc, New Yuik, 1978.

(51 Reference (41.p.u. (6) Gabel. Dorothy L., Fmi!itaiinp Problem Soluing in High School Chemistry, NSF Final

Report RISE SED79~20744, ED 210 192.

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