The CHEMATH Examination The evaluation of student skills upon entering a course of study provides valuable guidance to both the student and faculty. At the introductory chemistry level these exams have emphasized chemical principles a t the level of a one or two year high school experience. Examples of such exams are the Toledo Chemistry Placement Exam prepared by Alhertine Krohn and the General Chemistry exams available through the American Chemical Society's Examinations Committee (under the Division of Chemical Education). More frequently now introductory courses are being offered with no assumption of a high school chemistry background. For students entering such a course a traditiond chemical skills exam may not he aonronrinte. Durmg the f inter of 1 9 2 a study was made of the skills measured by the iJniversity mathema~icsplacement exam our students take. It wnqfound that rr mntainedafew lifan).?lof the mathematical rkilleaatudenr needs ina first orseemd semester of the introductory course. As a result a trial version of a multiple choice examination was developed to test specific skills necessary to attack chemistry problems. After the examination had been administered once, it was evaluated with the help,of members of the School of Education at UMSL, usinga technique called item analysis which statistically evaluates each foil of each ouestion for its abilitv to distineuish between eaod and Door students (as desiened hv the examination score) and estimates the overall difficulty &d validitiof each quest& ~ h r o k g hthis analysis the Gial version of the CHEMATH examination was carefully reconstructed to weed out ineffective foile., questions which were too difficult or easy and questions with limited validity. Even with these quidelines to improve the examination certain questions were retained that did not meet the guidelines but which represented skills that were felt essential. In addition certain physical changes were made to the format of the exam to bring it into the form used by other standardized exams. Since the Fall of 1973 the revised CHEMATH examination, containing 40 items, has been administered to 1178students enrolling in the first semester of a two-semester introductory chemistry sequence. The average, median, and made (22,22, 21, respectively) are the same within the standard error of measurement which was three, indicating that a given score is accurate to i 3 a t the 68% confidence level. An item analysis of the revised CHEMATH version showed considerable improvement in validity and difficulty distribution of the items. Items of highest validity and difficulty distribution included exponential evaluation, interpretation of graphs, algebraic manipulation and word problems. Low validity items included logarithms and functional relationships. As may be expected low validity items fell within the easiest or most difficult items, while items with high validity fell in the middle difficulty range. A study was made of CHEMATH scores and final grades in the course in order to detect trends. Since the number of students involved was relatively small, no sampling procedure was done; and because this was a skill measurement examination, statistical approaches to correlation were not attempted. But trends between CHEMATH scores and final grades might he expected and are shown in the table.
-.~.~ .~~~~
CHEMATH Smrer and Final Course Grades % of
Score
% A & B
Students
% D& F
%who wifhdrew
Probability of Receiving C or betfer
n C ~ m ~ l a trelultl i ~ e UP t o and including score in column.
in conclusion the CHEMATH exam has provided an opportunity to advise students more accurately on the question of preparation for the course and to suggest alternate curricular paths to successfully completing the introductory COU1W.
I would like to thank Dr. Jon Marshall, Assmiate Professor in the UMSL School of Education, whose research area is test design and construction; his comments and criticisms were most helpful. University of Missouri-St. St. Louis, 63121
514 / Journal of Chemical Education
Louis
Robert A. Rouse
