The Western Illinois University High School Chemistry Project

A Regional High School Chemistry Center

M. Venugopalan Western Illinois University, Macomb, IL 61455

For the past several years serious concerns have been expressed nationwide over the precollege preparation of stu- dents in chemistry. From my visits to chemistry classes over a period of years and from discussions with teachers in west- central Illinois high schools, the following two problems were identified:

(1) Many high school chemistry laboratories are inadequate for instructional purposes.

(2) Many high school chemistry teachers do not have the proper trainingkdueation to teach chemistry.

The first problem was addressed by establishing a central laboratory for the use of teachers and students of this re- gion.' T o address the second problem a number of teacher traininghetraining workshops were planned. This paper re- ports on the results of a one-week teacher training workshop on problem solving and classroom demonstrations, which was held a t the Center in the Summer of 1988.

The Teacher Parilclpants

Each of t h e 20 participating teachers completed a preworkshop questionnaire, from which the following infor- mation was obtained:

Educational background and preparation of the teachers varied from 6 to 60 college semester hours in chemistry. Eight of them had majored in chemistry, eight in biology, two in physics, one in agronomy, and one in English. Of the 1 2 nonmajors in chemistry, four had minors in chemistry. Their teaching experience in chemistry varied from 1 year to 24 years, with 14 of them teaching chemistry every year and six in alternate years. They have taught from one section (20-24 stu- dents) to as many as fivesectionsper year, have devoted from 10% to 90% of time for problem solving, and from 0 to 20% of time for classroom demonstrations. Fifteen of them had participated in one or both previous work- shops on chemical analysis using small instruments.'

The Workshop, Its Manual, and Other Materials

The main objective in conducting the one-week workshop was to retrain the teachers in oroblem-solving methods and lecture demonstrations to first-year high school chemistry. This was accomplished by devoting three hours each morning and three hours each afternoon to problem solving and classroom demonstrations, respectively. The topics which were chosen for the problem-solving and dem- onstrations segments were the following:

Presented at the 196th American Chemical Soclety Annual Meet- ing. Los Angeles. Sept. 1988. ' Baird, D.M.: Szamosi, J. J. Chem. Educ. 1987, 64, 1051-1052.

Problem Solving I. Manipulating numbers and displaying measurements with em-

phasis on significant figures, rounding off, scientific notation, units of measurements, dimensional analysis, and graphing.

11. Calculations involving chemical formulas, moles, and masses with emohasis on formula weieht. oercentaee comoosition. mass- .. . . mde particlr ronvennm, empiriral and mdecular furmulas.

Ill. Cns lnw calcula~ionp with emphasison Doyle's. Charles's nnd Gay-l.ussnc'r laws, combined gas law. SI'P ralculations, Aeogadrr,'~ law, molar gas volume, and volume-mass-mole-particle conver- sions.

IV. Stoichiometrie calculations with emphasis on chemical equa- tions and the mole concept, gas laws, limiting reactant and percent yield.

V. Solution ehemistrv and oH values with emohasis on exnress- ing concrntration, dilution and mixing ralc~rlations, molarit? and chemirnl equatlcmr. hydrogen ion conrentration and thr pH scale. and pH titration curves

Classroom Demonstrations A. Magnetic separation of iron from cereal. B. Demonstrations to illustrate the principles of like dissolves

like (I? and CuSOl in triehlorotrifluoraethane and water), differen- tial solubility and crystallization (PhL in hot and cold water), heat of solution (NH4NOz in water and anhydrous CaCIs in water), su- persaturation (using aqueous sodium acetate), and conductivity of ions in aqueous solution (titration of Ba(OH)* and H2SO1 using the electrical bulb conductivity apparatus).

C. Gas laws using diffusion of HCl and NHD (Graham's law), thermal expansion of air at constant pressure (Charles's law) and vapor density of a volatile liquid (Avogadro's law).

D. Types of reactions such as single displacement (Cu by Al), double displacement (colorful precipitates from several ionic solu- tions), neutralization (milk of magnesia and hydrochloric acid using universal indicator) and oxidation-reduction (electroplating cop- per, Cr2O7Zt (orange) to C~ '+ (green), and H202 BS an oxidizing and reducing agent).

An introductory lecture, which instructed the teachers on prohlem-solving methods or effective lecture demonstra- tions, was followed by supervised working of selected proh- lems or demonstrati& bv the teachers.-and discussion to ~ ~

identify chemical calrulaiions and demonstrations most benefirial to hieh school students. T o auement the needs of chemistry teacKers and students, a worikshop manual and sunolementaw materials such as comvuter promams, color tr&sparencies, and demonstration k&s were prepared and distributed. The write-up for each demonstration included not only the descriptions of the materials required and the procedure to be used, hut also discussions of the principles and technical notes, what rhestudentsshould learn from~the demonstration, and how the materials should be disposed of after the demonstration.

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Following the workshop, the manual and the associated materials were evaluated by the participating teachers. A great majority of the teachers reported that 75-100% of their students could benefit from the workshop materials.

Results of the Workshop At the end of the workshop, the teachers were asked to

complete a postworkshop questionnaire. The analysis of the teacher-supplied data isgiven below.

Problemsolving W m e n t of the Workshop Prior to the workshop there was a t least one teacher in the

group unfamiliar with one or more of the following topics: use of bar in significant figures, even-odd rule of rounding, use of formula subscriots as mole ratios, conversion from moles to particles or m&s and vice versa, using pathways for pas law and stoichiometric problems, partial pressures, mo- iecular weight from gas density, law ofconse&ation of mass, percent yield calculations, molarity, weightlweight percent and vol&ne/volume nercent as wavs of exnressine concen- tration. Two teachers had not heard of ~;y-~usiac 's law, Avoeadro's law and molar eas volume. limitine reactant. Hf con:entration and pH scare, and the use of iensity in ion- centration calculations. Three teachers had not used dimen- sional analysis in the conversion of SI units to English units. in ideal gas law, and in dilutionlmixing calculations involv- ing solutions. Four teachers expressed unfamiliarity with normality and pH titration, five with molality,six with mole fraction, and seven with weipht/volume percent.

IJuring the workshop, the teachers had difficulties with problems in solution chemistry and pH. Otherwise problems in the five units of instruction were, in general, familiar to a ereat maioritv of the wachers. The teachers found the level i f proble& "appropriate" for first-year high school chemis- trv with the followine exceotions: two teachers were not sure oisome of the prohle& ~~stoichiometr ic calculations using chemical equations; 13 teachers were not sure of some of the problems on solution chemistry and pH. However, only one teacher thouaht that the problems in solution chemistry and pH were "in~ppropriate".

As for the degree of difficulty to students, the problems in Unit I were thought to be "not difficult'' by 18 teachers, in Unit I1 hy 16 teachers, in Unit I11 by loteachers, and in Unit IV by six teachers. One teacher considered the problems in all categories except Unit I to he "very difficult"; nine teach- ers found the problems in Unit V "very difficult". In general, the problems in Unite I-V were considered "difficult" by two, three, nine, 13, and 11 teachers, respectively. Neverthe- less. all the oarticinants believed that some of the informa- tiongained during'the prohlem-solwng sessions will he car- ried to their students. The teachers'ratineol the~rabllltv for problem solving clearly showed that the; had receivedsig- nificant retraining in problem-solving methods.

Lecture Demonstrations Segment of the Workshop - The teachers listed the demonstrations that were "new" to

them as well as a t least five of the 15 demonstrations that they are "most likely" and "least likely" to use in their classroom (see table). The smaller number (five or six) of teachers who reoorted demonstrations B.2. B.3. D.1. and D.2 ~ ~ ~. , as "new" couldbe attributed to the fact chat some of these demonstrations were aerformed durine visits to area hieh - school chemistry classes.

All the teachers agreed that the chosen demonstrations were appropriate for first-year high school chemistry stu- dents and that the information gained during the demon- stration sessions will be carried to their students. None of the teachers thought that the demonstrations were "very difficult".

Recommendations from the WorkshoD The participating teachers arrived at the following recom-

mendations for hieh school chemistrv teachers:

Number of Teachers Responding to the Lecture Demonstrations

Use in Ciassroom Demonstration New Most Likely Least Likely

A. 1 Separation of Iron from Cereal 19 16 1 8. 1 Salubliity of Cu(ll) ion and is 8 9 1

2 Crystailization of Pbl, 5 6 5 3 Heat of solution of NH,N03 in water 6 7 3 4 Supersaturation (Sodium Acetate) 13 15 4 5 Conductometric (bulb) titration 13 10 3

C. 1 Gaseous Diffusion (NH3 and HCI) 9 8 7 2 Charles's Law 13 9 2 3 Molecular Wt. by Vapor Density 15 6 9

D. 1 Repiacement of Cu with Ai 6 7 2 2 Precipitates from Ionic Solutions 6 7 0 3 Neutralization of Milk of Magnesia 13 8 2 4 Electroplating Copper 7 6 4 5 H a 0 2 as an Oxid. end Red. Agent 15 2 7 6 Cr9O7'+ (orange) to Cr3' (green) 11 2 9

A. Teachers should teach the following problem-soloing steps: 1. Read the problem carefully. 2. Summarize given information. 3. Write relevant laws/equations. 4. Check dimensions of quantities/expressians far consistency. 5. Insert numerical values. 6. Calculate results. 7. Think about the validity of results! 8. State requested answer(s).

There was also near unanimous (19120) agreement to em- phasize and practice the use of proper units, significant figures, scientific notation, dimensional analysis and use of conversion factor(s). Teachers who were usine the "ancient" ~ ~~~ ~ . - - - ~ ~ proportion method agreed to switch to the- pedagogically sound conversion factor (factor-label) method.

B. Tips for Success in ClossroomDemonstrotions 1. Demonstrations must illustrate soecific orincioles (what the stu- . .

dents should learn). 2. Saferv (materiala required and their disposition). 3. Avoidance, to the eztent practicable, of halardnus materials. 4. Avoid dead time lest the attention of srudmts he lost. 5. Routine operations such as solution preparation, weighings, ete.,

should be done in advance. 6. Precede each demonstration by a discussion. 7. Some experiments proceed more slowly than others so that pro-

vision must be made to make the time otherwise useful.

The teachers assured that they will use the materials and orocedure sueaested in the manual for success of the demon- strations andh consult the Tech Notes in the manual for variations of the demonstrations.

Evaluation of the Project The teachers expressed great satisfaction with the con-

duct of the workshop. Nineteen teachers thought that the workshop was "unique" and/or "interesting" and 18 teach- ers believe that their students will benefit from the work- shop. The workshop has instilled the teachers with confi- dence in problem solving and made them facile doing dem- onstrations. I t has inspired a venturesome spirit in some of them for undertaking new demonstrations.

Acknowledgmenf The project is supported by funding under EESA-Title I1

grants from the Illinois Board of Higher Education. The author is grateful to A. Riley Macon for writing the

lecture demonstrations segment of the manual and conduct- ing that segment of the workshop. He is also grateful to Tim Liudahl, Macomb High School, and Mary White, Aledo High School, for their role as secondary teacher consultants on the project.

The technical support provided by Linda McDonald and Marc Melton is appreciated.

102 Journal of Chemical Education