An Electrical Review Chart for Students Beginning Organic Chemistry G . RICHARD BURNS Hunter College, New York City
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The example being prepared is illuminated by the yellow thimble over a bulb tn the upper right comer. The intermediate lights are in the upper left corner of the space ascigned to the structural formula. The buttons are on the inch-hiah dividinp strips below the comoout~ds. The control huttons are e r o u ~ e dou the rieht. The names of the 11 classesof compo&ds ire at the upper iight, the equation for the mark ac thhlower right.'
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HREE of the difficulties which trouble students in (Figure 1 and Table 1) and by pressing appropriate the first term of organic chemistry are: (1) stu- buttons, illuminate the intermediates from which a dents are not accustomed to the study of subjects in typical example of the selected class may be prepared. which constant review is necessary; (2) they do not The machine gives the student a grade on the answer differentiate between general reactions which are im- and then corrects the answer if that is necessary. The portant and those that are, in a sense, speaal reactions; various preparations are added to the chart as they are and (3) they do not arrange the review material in a taken up in the lectures. logical manner so that interrelationships are readily Since someof the preparations of a class of compounds apparent. To help the student over these difficulties, are usually taken up as reactions of other classes either to relieve, to some extent, the tedium of constant re- before or after the class in question is studied, the view, and to give some idea of the amount of progress student, by going over the preparations on the chart, being made, the machine described in this article was is able to ascertain the state of his knowledge of the constructed. fundamentals of the subject better than by reference to The machine is essentially an electrically operated his notebook which often has serious omissions. For chart (Figure 1) of the common one, two, and three example, in many courses at the time primary alcohols carbon compounds. The chart is so wired that the are studied, the only preparation given for a member of student may select any one of 11 classes of compounds this class is that from the corresponding alkyl halide or 232
add sulfate. At various later times the preparations TABLE 1 N"
NO.of
o i
Rcnc-
Elonlplrs Ethane Propylene Alkyl halides ( N l Almhols (N) Amincs (Nl
Ethyl halide Ethyl alcohol Ethyl =mine
Aldehyde3 Acids Cynnides Sec. aLy1 halides See. alcohols
A~etaldehyde Acetic acid Methyl cyanide Isopropyl halide 1~01)rotwlalcohol
I"le"nzrd'a1es
Methyl halide Methyl halide (Spec.) Methyl alcohol Ethylene Ethylene (Spec.) Ethyl halide Ethyl alcohol Ethyl arnine Acetaldehyde Acefie acid Aceticacid (Spec.) Methyl cyanide propaoe (spec.)
Propyleoe n-Propyl halide "-Propyl alcohol Propiooie arid Isopropyl halide lropropyl alcohol Acetone Methyl halide ( Acetaldehyde for Grignard
from the corresponding aldehyde, amine, acid, or the next lower Grignard reagent are taken up as reactions
of each of these compounds. The student ofteu neglects to place these reactions in his notebook as preparations of primary alcohols. The chart assembles this information and presents i t graphically. To use the chart the student first throws a time switch (Figure 1, No. 3), which turns on the current for the five minutes allowed for the test. He then chooses the class of compounds he wishes to prepare by pushing the selector button (Figure 1, No. 4). This illuminates the name of the class in the upper right-hand corner of the chart, lights a yellow bulb over a typical example of that class in the body of the chart, and, in the denominator of the equation No. Right - No. Wrong which the student No. of Pre~arations solves to obtain his grade, gives the number of preparations that are plugged in for that example. The student then pushes buttons under the compounds on the chart from which the example may be prepared in one step. If the intermediate is correct, a bulb over it is lighted and a score of one is added by the machine under the number right. If the intermediate is incorrect, the machine adds one to the number wrong. When the student has finished, provided five minutes have not elapsed and the machine has not turned itself off, he determines his grade from the equation and then revolves the correct answer key (No. 7) which lights
FIGURE 2 . p K ~ A . nVIE\\. OF CHART. SHO~TIXG WIR~NG The hank of intermediate relays is mounted vertically near the center. The 24-volt section of the selector switch is on the right and the 6-volt section a t the upper left. The projection counter is at thc rxtreme lower left. Above it is the correction switch and on the right, the number-right counter.
the bulbs over any compounds that have been missed. Lever No. 2 clears the board for the next question. For the purpose of using the machine only, a one-step reaction is deiined as a reaction or series of reactions which converts a compound on the chart into another without, in the process, converting it into any other compound also shown on the chart. Thus by this definition, the conversion of propionic acid into acetic acid is a one-step reaction. As intermediates, the alkyl halides are considered to include the Grignard reagents and the acid sulfates, the acids are considered to include their salts and the amides.
mediate in the class is used, and over the other intermediate. Thus, pressing the button to indicate that ethyl halide is made from ethylene calls attention to the fact that n-propyl halide is not made from propylene. The machine is placed in a hallway where the students may have access to i t a t any time and is known as "Professor Taylor." It is rather difficult to evaluate its service to the students just as it is that of a teacher. It was used about three thousand times in one term by a class of 70 students. As nearly as could be observed the better students were the ones who used it. One ~ossibledisadvantage appeared when the class went on into the aromatic series; some studentsdidnot seem to be able to handle the fewer correlationsin this series very successfully. This may possibly be due to the fact that, in previous classes without the chart, these students were not in the course a t this later date. The most notable effect of this piece of apparatus was that it removed the necessity for much tedious and repetitious tutoring on the part of the instructor, a type of work which, in the laboratory, would be mechanized as a matter of course. The chart seemed to be well worth the effort involved in its construction on this count alone.
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The nraterial usedin the construction of the chart FIGURE 3.--SCHEMATIC WIRINGDIAGRAM The wiring far the controls and for resetting is omitted. was obtained from pinball machines furnished through As my course is given, there are 33 preparations that the kindness of the police department. This source are general and in which any compound in the class of material has the advantage that no priority is required, the intermediate gives the corresponding product on but the material itself does not have the virtue of being the chart. For example, ethyl halide is one intermediate uniform as to the parts obtainable. For this reason the for ethyl alcohol and any other halide is the inter- following wiring diagram may have to be modified in mediate for the alcohol which is next to it on the chart. some respects. Limitations of material have also inThere are included, however, four preparations that are fluenced the design. For instance, the wire available is special in the sense that other compounds in the class in rather short lengths for so large a panel and, for this of the intermediate do not give the corresponding reason, the selector switch had to be divided into two product on the chart. These special preparations are: parts and operated electrically. Selection of questions ethane from methyl halide, ethane from acetic acid, would be more quickly made with a single manually propylene from propane, and ethyl halide from ethyl- operated selector switch. ene. If the button for one of these special reactions is The selector switch (Figure 3) has 11 positions; in pushed, a colored numeral is illuminated over the com- each position i t puts 24 volts on each of six wires and 6 pound, also over a footnote which explains that the volts on one wire. The wires with 24 volts may be reaction gives a different product if another intei- plugged in on one side of any of the intermediate lock I
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of
relays. The 6-volt contact illuminates the name of the mediates," so that the regular aldehyde and methyl class, the example of that class being prepared, and the halide relays may be used. The disadvantage of this is number of preparations for the example. The 23 lock that the student receives half credit for half an answer relays for the intermediates, connected on one side to and feels that the machine has a kindlier nature than as many as three positions on the selector switch, are the instructor. connected on the other to the grounding button under The panel of the instrument is six by four feet. The the intermediates on the face of the chart. While there spaces for the structural formulas are 61/2" wide and, are only 17 of these intermediates (Table I), three of in descending order, 73/4, lo3/&,lZ1/&,and lZ1/r" high. the four soecial reactions (there is no r e d a r reaction The letters are la/. X 17/.". There are 27 compounds for propane) call for a second relay connected to the intermediate button. Three more relays are necessaryfor the Grignard reaction, the wiring of which will be taken up separately. The lock relays, when activated by pressing the button under the intermediate, turn off the current on the coil, turn on a light over the intermediate, and activate a relay which in turn activates a delayed action solenoid in the scoring device. The scoring device consists of a number-right counter and a number-wrong counter, the latter advancing one when any button, correct or incorrect, on the chart is pressed. Pressing the button under a correct intermediate throws the lock relay and switches the ground connection to a high resistance relay. At the same time the other contact on the button advances the number-wrong counter by one. The high resistance relay, the purpose of which is to cut down current and hence fouling of the numerous lock relay contacts, raises a solenoid. When the button is released the solenoid, in dropping, makes a contact which advances the number-right counter by one and subtracts one from the number-wronn counter. A defect in this I I system is that if a correct button is pushed a second FIGURE4.-SPECIAL WIRINGFOR THE GRIDtime i t scores a second time. NARD REACTION The correction switch mounds the lock relavs one a t a ti&e and throws any that have been missedi. When wired as shown in the diagram, i t will also change the on the chart. From 10 of these nothing can be prepared so that the buttons under them are connected to number right and the number wrong in the score if either of two lock relays, hooked to the same button, the number-wrong counter only. The transformer and the coils are protected by a thermostatic over-load cutare connected to the selector switch. The numberout which is apparently not necessary as it has never wrong counter is a oroiection t w e and runs no to 27. . been found thrown. The number-right con&er goes to six and'records To operate the chart, there are the following controls: by illuminating numerals. The wiring of the Grignard reaction, isopropyl alco1 Anti-buzz. The instructions read that this is to hol from methyl halide and acetaldehyde, is shown in be pushed when the machine emits a loud buzz Figure 4. The number-wrong contacts from these when no keys are being pressed. Such a conbuttons are not connected directly to the numberdition would result from a contact being wrong counter as in the other cases. Pressing either stuck and operating a relay or solenoid conbutton simply scores one wrong unless the selector tinuously. The button can be reset only by switch is on isopropyl alcohol, in which case both buta key. Because of its number this button tons are disconnected from the number-wrong counter tends to prevent students who have not read as soon as the one wrong is scored. The other contact the directions from operating the machine. on each button is so wired that on.pressing either one of 2 Lever to start time switch and turn on current. the buttons the corresponding intermediate bulb is 3. Lever to reset lock relays and counters. lighted and the connections of the other button so 4. Selector button. Advances question selector changed that, on pressing, its bulb lights and the deone position for one impulse. There is an layed action solenoid is activatedadding one to the automatic return if the button is pushed after correct score and removing the one scored under the question 11. number wrong. An alternative to this use of four re5. Selector return button. Returns selector to lays for one reaction is to change the "Number of start when pressed. preparations'' on the chart to "Number of inter(Continued on @age242)
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JOURNAL OF CHEMICAL EDUCATION
tion of iron ore. The blast furnace, skip hoist, stoves, dust catcher, and pipes are all made of thin balsa wood, properly painted. Balsa was chosen because it is soft and easily cut, but other thin wood or even thick cardboard would do. The background is a board from" packing box. Although the structure is only 18 X 28 inches, it is clearly visible to a large class. It is small enough to pass around the class if desired. Many other models and drawings are in stock, all made by students and all useful. In some cases the models produce the proper products. It is felt that these activities of making visual aids not only have considerable educational value to the makers, but also produce distinct additions to the teaching equipment Processes are easily explained, and added interest is shown because of the students' contribution.
FIGURE 5.-BLAST FURNACE
A STUDY OF THE ACHIEVEMENT IN GENERAL CHEMISTRY IN THE A. S. T. PROGRAM (Continued from page 238)
0..06 between class test scores and scores on his "PrincipIes Test." A coefficient of correlation of 0.71 "" 0.04 between Form A of the Powers General Science Test and School Marks and of 0.59 "" 0.05 between Form B of the Powers General Science Test and School Marks has been reported (12). "It is, of course, rather obvious that a degree of relationship approaching closely to that indicated by a correlation coefficient of + 1.00 would be impossible of attainment with present measuring instruments and school organization, and also that no one not believing in a deterministic form of education could wish for such a situation" (13).
therefore, can be justifiably used in assigning class marks. LITERATURE CITED
(1) "Editor's Outlook," J. CUB". Eouc., 20, 521 (1943).
(2) CALANDRA, "The college chemistry testing program," ibid., 20,141-4 (1943). especially Table 1. (3) CALANDRA, ibid., Tables 4 and 5. (4) CALANDRA, ibid., Tables 2. 4, and 5. (5) SACKETT, "The quality of A.S.T.P. men," School and
Society, 58,318-20 (1943). (6) CRAF, "A.S.T.P.," J. Higher Educ., 14,399-403 (1943).
(7) "Editor's Outlook," op. cit., p. 521. (8) ROBINSON, "Study skills of the soldiers in A.S.T.P.,"
School and Society, 5S, 398-9, (1943). (9) MACPHAIL AND FOSTER. "Placement in beginning chemis-
CONCLUSIONS
The achievement of the average trainee in A.S.T.P. Chemistry 206 is slightly higher than that of the average college student in first-year college chemistry. However, he is not significantly superior, and can be judged in terms of the civilian college student. The coefficients of correlation found are comparable to those reported in the literature as accepted evidence of validity for achievement examinations. Cumulative class scores as determined by our tests can be considered valid measures of achievement and,
try courses at Brown University,"
J.
CHRM. Eouc., 16,
270-3 (1939). (10) On file in the Chemistry Department, University of Con· necticut, Storrs, Connecticut. (11) KILGORE, "Identification of Ability to Apply Principles of Physics," Contribution to Education, No. 840, Teachers College, Columbia University, New York City, 1942. (12) POWERS, "Directions for Giving; Powers General Science Test," Bureau of Publications, Teachers College, Columbia University, New York City, 1927, p. 1. (13) GERBERICH, "Factors related to the college achievement of high-aptitude students who fail of expectation and low-aptitude students who exceed expectation," J. Educ.
Psychotogy. 32, 253 (1941).
AN ELECTRICAL REVIEW CHART FOR STUDENTS BEGINNING ORGANIC CHEMISTRY (Continued from page 235)
6. 7.
Instructions read Determine mark. n Correct answer switch. One revolution lights any intermediates that have been missed. This is kept in open position by a weighted handle. The products are indicated by illuminated colored plastic thimbles, the intermediates by bare bulbs, and the number wrong by projected numerals. The names Il
of the classes, the special reactions and footnotes, the number of intermediates right, and the total number of preparations are indicated by signs illuminated from the rear. New preparations are added by plugging in a jack from the intermediate relay of the appropriate compound to the correct position of the selector switch and changing the number-of-preparations jack for this position to the next higher numeral.
