ADMINISTRATIVE AND TEACHING PROBLEMS OF LARGE CLASSES IN QUANTITATIVE ANALYSIS WILLIAM MARSHALL MacNEVIN The Ohio State University, Columbus, Ohio
THE
FIRST course in quantitative analysis holds a prominent place in the scientific development of the college student because it isusually his first real contact with exact scientific method. His reaction to the course, to its organization, administration, as well as to its teaching, may therefore influence his future attitude toward chem&ry. In 1896 when Professor Charles W. Foulk began his lone career of teachine analvtical chemistrv a t The Ohio State University there we& about a dozen students in the class. By 1910 the class had increased to 75; in 1920 it was 125. About 1930 it suddenly doubled when quantitative analysis was made a required subject for wremedicalstudents. and in 1939. when Professor Foulk retired after 42 yeah of teaching, it had reached what seemed a t that time a cumbersome total of 400 students. Many of the administrative and teaching devices now in use in the course were developed by Professor Foulk and much credit should go to him for originality. iKumeroos graduate student,^ who later became teachers of analytical chemistry have become familiar with these methods and have applied them in many colleges and universities of the country. Professor Foulk's influence. in this respect has been far-reaching. The confusion inherent in large nnmbers tends to prevent the attention to the individual which characterizes the teaching in small colleges. It has therefore been a guiding principle in the solution of our problems due to large numbers of students, to provide as much attention to the individual student by senior staffinstructors as is consistent with reasonable demands on the time and energy of the teaching staff. We hold to the opinion that a large part of the teaching in quantitative analysis must be done by the senior instructors consulting direct,ly with the student. We further encourage attention t,o the individual by keeping lecture sections small, hy having a senior staff instructor available to the student whenever he is in the laboratory, and by maintaining a detailed and well-defined grading system. The student is encouraged if he feels that he is part of a wellorganized and well-conducted course; that his professor knows exactly how he is progressing and is aware of and helps him with his difficulties and there is no guesswork in the grade he receives. After the necessary mass production techniqnes of freshman chemistry, the student is pleasantly surprised to realize that he is once more an individual and no longer just a point on a distribution curve. Organization and definition of staff duties can solve most of the problems of large numbers in qnantitative analysis. ~
~
SIZE AND COMPOSITION OF CLASSES
The class in quantitative analysis has continued to increase since the retirement of Professor Foulk. Table 1 shows the enrollment at The Ohio State University in the years 1937 to 1948. The peak has not yet been reached. Table 2 show t h e distribution of students among the various groups in the autumn quarter of 1947. The hours given to lecture and laboratory by each group are also included. DefinedConditions. Several conditions and practices exist in our University which define for us the limits within which we must do our teachin~and are here discussed. ' TABLE 1 Enrollment in Quantitative Analysis, The Ohio State University, 1937-1947
Yea?
-
Enmllment*
1937-38 434 1938-39 435 193940 402 1940-41 378 540 194142 194243 371 194344 196 197 1944-45 194546 443 194647 884 194748 (980) 0st.t Number of students who started the sequence in a calendar year.
7 Includes estimated figure for spring and summer of 1948. TABLE 2 inAutumn Ouarter,
of
J,ectures Class Gwup
('hem. Eng. %.En& Premedics pharmacists Ved. Techs.
Week per Lab. Hm. Quarter Credits
(So W k . ) per Week
2 1 1 1 1
9 9
1
6 6
1
6
6 2
5 4 3 3 3 3 3
En~ollmat
79 180 32 321 141 15 18 786
1. The Quarter System. The college year consists of three approximately ten-week periods or quarters. The summer session is similar in length and is in effect a fourth quarter. Certain advantages result from, this system. A student may start his quantitative analysis
589
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in-any quarter of the year. He may also drop out for a quarter without incurring a long delay before reentering the course. One consequence of the fact that the sequence in quantitative analysis starts every quarter is that excessive enrollments in the autumn quarter are avoided and the enrollment is in general leveled over the year. The facilities of the course are thereby used more efficiently. We could not in fact provide enough equipment to carry our 800 students if they were all working a t the,same thiig a t the same time. In the quarter system summer work is the equivalent of that in any other quarter and need not be reevaluated. The quarter system also permits staffing the summer session by releasing a suitable number of lecturers from duty in one of the regular quarters. A continuity of program and administration is thus easily maintained. The quarter system also has disadvantages. A full year's work in quantitative analysis must he organized three times. Three sets of final examinations must be given. The effective teaching time of each quarter is reduced to about eight weeks by the formalities of starting and stopping. Lockers must be assigned and checked out three times and laboratory accounts opened and closed three times during the year. The loss of time in this repetition is large. A second disadvantage of the quarter system is that there is usually no relation between the schedules of a student from one quarter to the next. He is likely to be assigned to a differentlecture section and may therefore have a different lecturer. The problem arising from this lack of continuity is met by having all lecturers in the same class cover the same material in a given quarter. A list of weekly lecture assignments is prepared and given to each student, and each lecturer follows this plan so that by the end of the quarter all sections will have covered the same ground. All lecturers take part in the preparation and editing of these assignments, but the individual treatment that an in~t~ructor gives each subject is left entirely to him. Under the quarter plan the students of any one section may have laboratory schedules covering every half day of the week. It is impossible for a professor to see all of the students of his lecture class in the lahoratory unless he goes t,hrough the laboratory each of the eleven half days of the week. The disadvantage of this situation is partly remedied by a system of laboratory supervision in which one of our professors is always on duty a t the laboratory and the student is sure to see a professor each time he comes to the laboratory. Such a plan obviously requires uniformity in teaching among the various professors of the division. 2. Limited Lecture Periods. The lecture time allowed us in all service courses is 6fty minutes per week. This allotment is made by the Medical School, the Engineering College, the Pharmacy College, and the College of Education. This lecture is the only formal meeting of the class each week. All lectures, demonstrations, weekly and mid-term examinations must be given in this one period. Such a limited time allowance
JOURNAL OF CHEMICAL EDUCATION
naturally calls for a high degree of efficiency in the presentation of the material. The lectures must be carefully planned. Interruptions and spontaneous discussions must he limited. Only the principal points are discussed in lecture. Reading assignments are given to fill in the gaps and the basid techniques are demonstrated. The lack of opportunity for discussion, especially of experimental work, is partly compensated by a system of laboratory quizzes given individually to students in the laboratory. This will be described later. The chemistry majors have two lectures per week for three quarters. I t is felt by all connected with this course that the one hour of lecture per week in the service courses is not sufficient for the teaching of amodern course in quantitative analysis. The time limit is established for us, however, by the administrative boards of the colleges for whom we give the service courses and we can do little to change it. 3. Limited Laboratory Periods. Few students have more than three hours of continuous laboratory time. They cannot therefore perform long experiments-at least, those which have long individual operations. There has been a trend in late years toward leaving out the classical limestone analysis from our program. Short modifications of several of the longer experiments have been us$. 4. Storeroom and Supplies. We have an excellent system of supply run by the University. I t maintains 31 supply store outlets and there is always one near a Iahoratory. The activities of the Supply Stores are limited however. The teaching staff must check in and check out student lockers. All side-shelf reagents and supplies must he maintained by one of our quantitative staff. We employ a full-time technical assistant and several part-time assistants for this and related activit,ies. The University regards the lockers, desks, balance benches, balances, ovens, etc., as part of the equipment of the room. Janitorial service is limited to cleaning the permanent parts of the stmcture such as windows, floors, and walls. We are required to clean the laboratory desks, lockers, balance benches, hoods, etc. Our technical assistant and his assistants take care of this problem for us. Balances are cleaned by the teaching assistants. Each teaching assist,ant is responsible for the continuous care of three or four balances. 5. Laboratory Space. It became evident in 1936 that the main quantitative laboratory (capacity 320) would no longer hold the expanding classes and the following alternatives were considered: (a) Sharing the locker equipment by two students is done in freshman chemistry but is impractical in quantitative analysis. (b) By conversion of quantitative to a semimicro scale, less space mould be needed for storage. Therefore, more lockers could be placed under a work space. Less work space would be needed by the student. Since no one really knew a t that time how well semimicro quantitative methods would work in student.hands, we did not attempt it. Since that
NOVEMBER. 1948
time, we have studied the idea extensively and think it may deserve some consideration. (c) By establish'mg storage lockers in hallways near the laboratory, the student can carry his tray of needed equipment to an assigned work space in the laboratory. In order to add significantly to our capacity by t,his scheme, it was necessary to acquire more work space and time, and hence some evening classes were tried. These were not satisfactory for the student and were definitely unsatisfactory for our teaching staff. (d) During the period from 1938 on, the Freshman Division of the Department of Chemistry was gradnally adapting itself to semimicro methods. Special laboratory desks were designed by Professor Garret,t and his staff for the specific use of semimicro methods. This resulted in a decrease in the space and time requirements per student. The decrease was so great that, although the enrollment in freshman chemistry jumped to 4500 after the war, the total space apd time requirements were even less than they had been for 2300 students, the prewar top enrollment. Space was therefore available from this source to continue our standard practice in t,he expansion in quant,itative analysis. We have acquired two former freshman laboratories in this way and may have another if it is needed for further expansion. Both acquired laboratories are in scat,tered locations which adds materially to problems of the supply of special reagent,^ and equipment and of supervision. For example, a break down of service costs indicates that, about one-third of the service cost is for travel and transportation of chemicals between laboratories. These conditions define for us some of the more general problems we must meet. Many of them are annoying, but they are of long standing and efforts to change them are usually fruitless. It is easier to accept. the condition and adapt oneself to it.
a large diagram of the laboratory by writing the student's name and schedule into the space indicating his locker. This system is satisfactory and rapid. Four instructors have assigned up to 5001ockers in an approximately six-hour period. The assignment process is usually completed by the second day of the quarter. By efficient assignment of the work spaces we have been able in late years to use about 98 per cent of the lockers. But under our plan there are some periods in the veek, two or three, when each work space is idle. However, this is not a waste of work space since it is common in quantitative analysis for students to require some extra time and, of course, extra work would not be possible if every work space were assigned for every period. SPECIAL EQUIPMENT AND OPERATIONS
Balances and, Weights. For the present enrollment of 800 we use 130 balances and sets of weights. These are located in the laboratory on special benches along the walls. Six to eight students are assigned to each balance. Assignments are so arranged that a student's balance will be located near his work space. Not more than two students are assigned to a balance for the same period. Of these, one d l be a student in gravimetric analysis while the other will probably be doing volumetric or instmmental analysis and will require relatively little use of the balance. Weights are supplied nith each balance. The students do not calibrate their weights. Once a year the weights are adjusted so that they are correct as marked within 0.1 mg. Chemistry majors and chemical engineers get experience in weight calibration, but i t is in the third quarter rather than at the beginning of the course. Balance Instruction. In the autumn quarter of 1947 we had 475 students starting in quantitative analysis. The need for a large amount of instruction in a short time in the correct use of the balance is evident. The
ASSIGNMENT OF LABORATORY LOCKERS
The quantitative laboratories a t The Ohio State University contain a t present 800 individual lockers. They are arranged in groups of four lockers to a work space, so that 200 work spaces are available. This is the capacity of the laboratories a t any one time. The work space is the desk top space covering the four lockers and is the space available to each student during his assigned lahoratory periods. Obviously no two of the students assigned to lockers in one work space can work at the same time. Extra work is permitted, but the extra student must find a vacant work space elsewhere in t,he laboratory. Assignment of lockers is made on the first day of the quarter. The student fills out a card with his time schedule and presents it to one of four instmctors, who assigns the student a locker space with due regard for his schedule. Fee cards are also inspected a t this time and balance assignments are initialed on the fee card. Balance assignments are made according to the locker assignment. Records of locker assignments are kept on
DISTILLED WATER
CALIBRATING PIPET FLg"..
1
592
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are expected to know how to do the usual calculation of volume from weight of water, this method of calibrating flasks loses none of the value of the usual calibration experiment. Indeed it demonstrates an even broader application of the principle. With new locker assignments each quarter, it is not possible for the student to retain the same flask and pipet from quarter to quarter. The method of calibrating the flask makes it a simple matter for him to mark his new flask a t the beginning of the next quarter. However, the new pipet has to be calibrated each qnarter by the student by weighing the delivered volume of water, but this is a relatively short operation. The h r e t is not part of the regular equipment and is not stored in the locker. Burets are stored in a rack a t the side of the laboratory under the locker number of the student. They are stored in this way between quarters, and therefore the same buret can be reissued to a student until he is through with it. Notebook. A special notebook designed to fit the course is used. It contains special data forms for most problem is simplified greatly by leaving ont weight cali- of the experiments. Extra pages are provided for debration a t the beginning of the work. scription of experimental procedures, etc. For several Balance instrnction is given in the following way. reasons we use a special notebook of this type rather First, thestudent hears a general lecture on the balance than a blank notebook. The data forms are so designed and its use. He is assigned certain reading abont the that the student must provide complete data on his exbalance and is asked to study the details of a laboratory periments. We hope the habit will persist. Another exercise called "Balance Instruction." During his next reason for a printed notebook of this type is that it laboratory period he joins a group of ten students who makes it easy for the instructor to find a given experireceive instrnction seated a t a row of balances. The in- ment. Contrast this with the difficulty there wonld be structor puts them through the operations of using the in locating a given experiment in several hundred blank balance, one operation a t a time, and the students keep notebooks in which the order of experiments would together during the whole process. The individual probably never he the same! An interesting feature of the notebook is that the data operations performed are: checking the level of the balance, examining the controls for beam and pan supports pages in it are a duplication of the report forms. Transand for the rider, determining the equilibrium point, fer of the data to report forms is relatively simple. The determining the sensitivity, examinmg the weights and student is encouraged to regard his notebook as the forceps, weighing a crucible and cover, and recording original data. We do not follow the plan of tearing data and checking the ~veights. After this instrnction has pages out of the notebook. been completed the student is permitted to use the balLaboratory Quizzes. Before a stndent can obtain a ance and proceed with his first determination. Balance sample for analysis he is asked to write an outline in his instruction given in this way requires about one hour for notebook of the analysis he proposes to do. This onteach group of students. On the average, a laboratory line includes the steps of the determination, new points instructor will have not more than two or three such of technique, and rhemical and mathematical equations. groups for balance instruction in any one quarter, so the The stndent is also expected to prepare himself f o an ~ task is not a heavy one. oral quiz. Not only will the principles be reviewed but Calibration of T7olumetric Epuipment. Calibration of the instructor will ask several "why" questions about volumetric flasks presents a problem. Obviously it the chemist~yinvolved. The student may also take adwonld be impractical to have enough large balances for vantage of this discussion to ask questions of the the usual calibration method of weighing water. In- instructor. If the instructor is satisfied that the student stead, we use a calibrating pipet as shown in Figure 1. is familiar with the determination he will check thenoteSeveral of these are placed a t strategic locations. Each book and issue a sample. If the quiz is unsatisfactory is eqnipped with a supply of distilled water. The cali- the instructor requires the student to prepare himself hrating pipet has been marked to deliver exactly 500.0 better and take another quiz before the sample is issued. ml. a t 20°C. When this device is used by the student to Samples. A great asset in teaching large groups of locate the 500.0 mark on a volumetric flask, the flask quantitative students is a well-established stock of will have been calibrated to hold 500.0 ml. a t 20°C. analyzed samples. Fortunately, the preparation of such The only provision required is that the temperatures of a stock has been well developed a t The Ohio State the calibrating pipet and of the volumetric flask be the University. The sample problem is a big one. We same a t the time of the experiment. Since the student.; issue over 60,000 individual samples a year to our
NOVEMBER, 1948
we can prepare long series of samples with irregular and yet small variations in percentage. When we buy samples we frequently are able to get only a few variations and the appearance of some of these will be such as to he recognizable by the student. In a class as large as ours there should be at least 35 to 40 variations in a sample in order to prevent comparison of results. Sample Records. Each student sample has a different serial number which is clearly written on the face of t,he label. This number is recorded in a special record by Fig3. S.md,le Code Book t,helaboratory assistant (see Figure 2) when the sample is given out. The assistant also records the date and his students. These are prepared, labeled, and numbered initials. Once a day these record books are collected from series of stocks. The stocks in t,urn are prepared and the sample numbers transferred to the studentk either from natural ores. commercial mat'erials or. in a individual record sheet under the date of issue of the few instances, by mixing pure chemicals. The stocks sample. The st,udent also records the sample number are carefully mixed, usually brought to moisture equilil)- in his notebook. The number n.ill eventually appear on rium with the air and are carefully analyzed. They Laboratory LockerFim2N.m. linili4.B , Sam.* No. are stored either in glass 8hstN.me < ~ r m t J M T " 9 1 T k F 8 or metal containers. The Lab Seheduls magnitude of our. sample supply problem is indicated by the quantities of mateDETERMINATION OF WATER IN BARIUM CHLORIDE rials with which we start in Datp of report in^ making up new sets of Date of rreeiving sample stocks. For the preparation PllorrDunE: Heat sample overnight in 275' oven. of a graded series of twentyfive fertilizer samples, we Constant weight of Empty Crucibles Crucible number started with 1000 pounds of fertilizer. When brass samWeight of empty crueihlc +cover, 1st heating ples were prepared recently, Weiaht of empty crucible + e w e r , 2nd hearing we worked up twenty-five Weightof empty crucible + e w e r . 3rd heating 20-pound ingots. It might be expected that Weight of Sample Weight of erueible + eavrr + aample we would make use of some of the sample services rather Weight of empty erueibie + cover (constant ut.) than do the work of prepa, Weight of sample ration ourselves. There are several reasons why it is Loss in Weight Weightof erueible +rover + sample before hearing better for us to do it ourWeight of erueible + e w e r + aample after heating selves. In the first place, being a largeorganizationwe Loss in weight can afford to have an in- Per cent H.0 structor who has as one of is specialties the whole prob- Equations: BaCI.. xH.0 + heat = lem of sampling. Usually we have someone who is particularly interested in this subject and the problem of preparation of samples is turned over to hi. A second reason for preparing our own samples is that we like to analyze them by our own methods. We like to know Signed Point. by first-hand observation all the varieties of behavior en- F- * l a If i t becomes necessary to repest thisdetermination a near sample must be obtained. countered in a series of samples. A third reaRon is that Figure 4. Report fa*." for water D.*.rminltion
w
JOURNAL OF CHEMICAL EDUCATION
594
the student's report of the analysis These sample numbers are used by the graders to identify the stocks from which the samples were prepared. Figure 3 shows a page of the Sample Code Book filled out a t the time the individual sample was prepared from the stock sample. Sample Labels. The hand vork of labeling 60,000 samples a year is enormous. We have had prepared printed gummed labels for each kind of sample. The only handwork required is the writing of the serial uumber on the label and the stock number in the record book. These labels carry information about drying the sample. Standard samples are also given out in individual bottles and special labels areused.
CHLORINE
z, ,, $ ,
+s
2
2
[LLLLII_I_U Fiw..
s.
PI.,,
Chlorin. R e p *
For G..din.
1 on
.I
I
1
point Bmm"
ports is an extremely important part of a course in quantitative analysis. It has probably more effect on the quality of the work accomplished and upon the TABLE 3 morale of the students than any other single factor. Grading Basis i n Quantitative Analysis Guesswork in grading should not he tolerated. An A B C D organized grading plan also has the advantage that it Examination average 90 80 70 60 can be administered by clerical assistance. Only borderlaboratory points-4 or 5 credits 100 90 80 70 line cases need be referred to a professor. In our group 4 awdit,~ 70 fin fin 40 we have two full-time clerks who grade laboratory reports and keep the records. Figure 6 shows the top half of the record of an individual student's work. It inTABLE 4 cludes the quiz grades as well as the laboratory grades. Calculation of Examination Average Attendance Rolk In a large group it is essential to Weekly quiz av. (4 01. 5 quizzes) x 2 = keep a daily record of attendance and a record of what Mid-term X 1 = the student is doing. Consequently, we have a rollbook Final x2=I for each of our three large laboratories which shows Examination Awrage = when the student is supposed to be present. When the roll is taken, instead of marking the student present or absent, we record a symbol indicating the experiment Report Forms. The st,udentls original observations each student is doing. This roll is taken by one of the are placed directly in the notebook. Reports of analyses senior staff and gives the student a chance to talk inare made by the student,^ on special report forms. dividually with a professor. It also accomplishes another Figure 4 shows the forms for the water determination. valuable end in bringing the professor directly in Two copies of each report are handed in by the student contact with what is going on in the laboratory. This for grading. After they are graded, one copy is returned we have found does more for raising the scientific morale to the student and one copy is filed under the student,'^ of thelaboratory than any other single activity. During name. Thus a complete record of the student's work is the quarter each professor attempts to get well acalways easily available. quainted with the students in his laboratory section and Grading. The need for uniform gradmg is met by a is responsible for estimating the laboratory technique well-defined plan. The final grade in the course depends grades of those students. Each professor has on the upon the accomplishment in several examinations and in average three such laboratory periods in a week in the laboratory work. The general plan is shown in which he supervises all of the activities of the lahoraTable 3. Both parts of the work have to be equally tory. good in order to justify a given grade. We do not average the two except in borderline cases. TABLE S The "Examinat,ion Average" is an average grade StaffPersonnel i n Quantitative Analysis made up as shown in Table 4. vdinatm The "Laboratory Points" are arrived at in the followTechnical Clerical Loboratow ing way Each laborat,ory exercise is weighed in terms Instruetom Asst. Asst. of points. For example, the determination of chlorine full professor supervisors full-time full-time is worth 15 points if the st,udent gets it right, that is, if asst. rlerks the reported results are within certain limits. If the 2 assoc. proiossors 30 as~istants 7part-time . . .. student's values are outside the limits for 15 points, ,st. professors* assts. . . ... .... .. .. .. .. then fewer points will be given according to the size of ~ ~. . . the pigure 5 a set of values used in 'T'YO ifthese position8 tem&raril$ filled by Instructors. C U
I
-
,
~
grading chlorine analyses. I t should be emphasized t,hat a well-defined grading scheme for laboratory re-
St&
~
An outline of our present staff plan is shown in
NOVEMBER, 1948
Table 5. Professors are essentially responsible for teaching, but have an overall responsibility for each activity related to the course. The ratio of number of students to a professor, 100:1, seems high. Although we are doing a good job of teaching, we could probably do it better with a more favorable ratio and so it is our present plan to reduce the ratio to about 65: 1by adding to our staff. In the laboratory, the ratio of number of stndents to an assistant is about 22: 1. Uniformity in teaching by our staff is essential under the conditions which have been described. Each staff member must feel that he has a responsibility for carrying out the general plan which has been agreed upon by the staff. Severtheless, each instrurtor has full opportunity to develop his o1vn ideas and put them to use in the group as a whole. For example, a suggestion may be made that a new analysis be added to the course. New ideas are first discussed in the weekly staff meeting. They are then tried out with a few special students in order to determine how the procedure will be interpreted by students. After any corrections and changes are made, the new procedure is included in the revision of a set of "Special Notes" which are issued once a year. The Junior Staff must then be briefed on the new plan. In the meantime, nelv ~eagentsmust be provided in the several laboratories, new report forms worked out and printed, new sample labels printed and a new set of stock samples prepared and analy~edand then bottled and labeled ready for issue to the student. CONCLUSION
The administrative duties of the coordinator of a group such as ours constitute a full-time job and it is easy to spend all of one's time on it. No matter how you do it, a lot of time is used. The task is greatly eased by having an able staff and one which will take the responsibility for seeing that, the genera1 plan is carried out. Cooperation is essential. No one person can perform all of the activities. Duties and responsibilities must be farmed out to individual professors and assistants. The staff should know that Professor A is
responsible for all questions relating to special equipment; that special questions about samples and laboratory reports should go to Professor B and so on. The laboratory supervisory activities of our senior staff are an invaluable asset to the course because they establish the morale of the course. It would, however, be impossible for us to operate our course without the services of our technical assistant group. They provide the special chemicals and equipment in each laboratory; they prepare and analyze the stock samples and maintain supplies of individual samples in each laboratory. This group is also available for any of the numerous special chores that are constantly required in the opewtion of the course. Finally, the clerical assistants do the routine job of grading laboratory reports and keeping the records up to date. Only special cases nred be referred to a professor. The professor need not spen I very much of his time on anything but teaching. Thus we see that mariy of the problems of a large class in quantitative analysis can bemet by coordination of activities, by uniform teaching programs, by standardizing the paper work through the use of printed forms and by employing sufficient technical and clerical assistance. Those who like administration will find it interesting. Those who don't like administration will find that the more efficiently the job is done, the more time there will be for something else.
