Chemistry Course: The Prelecture Assignment Frank J. Kristine The Pennsylvania State University. Mont Alto Campus, Mont Alto. PA 17237 I t has been suggested that "the factual material, mathematical calculations, and theory that constitute modern chemical knowledge contribute toward making chemistry one of the most intellectually demanding subjects in the university or high school curriculum." 1 T o he successful in chemistry, a somewhat disciplined approach to studying is required. However, discussi&s with my own studentsrevial that many freshmen have not developed study habits appropriate for the r&ognized and mastery of chemistry. ~ h & facts e are some general chemistry texts2 now include "How to Study Chemistry" in introductory sections or the accompanying study guide.3 Reinforcing these ideas in course syllabi and durine" initial lectures also seems to he a current nractice among general chemistry teachers. However, the major problem is one of motivation to develop proper study skills. The approach I have taken is to include instructional activities during the course that introduce the students to studving - strategies. The prelecture assignments intend to motivate the students to preview the relevant text material before attending lecture. This is usually the first suggestion in a discussion of how to study effi~iently.~.3,~ The students are informed that this should reduce notetaking enabling them to listen more intently to the instructor's explanations of the material. These assignments also give the student the opportunity to review specific skills or concepts covered earlier that are now going to he applied to the new subject matter. Format of the Prelecture Assignments The orelecture assignments described in this report were used with the second semester of general chemistr; at Penn State. Thirteen assignments were prepared, one for each major section of the course. Each assignment consisted of 7-12 questions divided between a review and preview section. The questions in the review section covered prerequisite material and the students were instructed to complete them before beginning the reading assignment. Each question listed sections of the text5 to be reviewed if needed. The review of math skills included problems that were a part of a calculation that would appear in the upcoming lecture. The following are represen&ve examples of review questions. Chemical Equilibrium Consider the reaction: Ndg) + 3Hdg) = 2NHdg). If x moles of nitrogen read, how many moles of hydrogen react and how many moles of ammonia are formed in terms of x? 'Williams, H., Turner, W. C., Dubrevil L.. Fast, J.. and Berestiansky. J., J. CHEM. EOUC., 56, 599 (1979). Brown, Theodore L., and LeMay. H. Eugene, Jr.. "Chemistry: The Central Science." 2nd ed.. Prentice-Hall. Inc.. Englewood Cliffs, NJ, 1981.
Wismer. R O W K., "Student study Guide to Acwmpany Petrucci's 'General Chemistry.' " 3rd ed., Macmilian Publishing Co., Inc., New York, 1982. Shepherd, James F., "College Study Skills." Houghton Mifflin Company. Boston, 1979. The text currently used at the Mont Alto Campus of Penn State is Brown and LeMay, see footnote 2.
Student Evaluation of the Prelecture Assignments a Average Responseb
Question 1. 2.
3 4
Overall,how useful were the prelecture assignments in helping you learn the course material? Did the preiecture assignments help you with your first readino of +hetext material? By completing the preleclura assgnments 00 you thmk were oener able to la1 ow m e lecture prescnWllons9 DOyou thmk me mrsuctor shaLla conmnue usmg the prelecture assignments as a part of this course in the future?
3.78
3.76 yo^
3 97
4.22
63/75 otUdeMS responded. b ~smquenbnwas respordedtoona scaleof 510
1 wim 5 being me moot wliveand
1 being the mmt negative response
Solve the following equation for x : 46.5r2- 0.152~+ 1.01 X
=0
Acids and Bases You should he able to do log and antilog calculations either using a calculator or log tables. Complete the following calculations: a) log 2.3 X 10W5= h) antilog -3.64 = Coordination Chemistry What is the electron configuration of the Fe3+ ion? x
The d orbital that has electron density concentrated between the and y axes is designated as .-
The questions in the preview section referred to the reading assignment. Most were fill-in-the-blank statements based on a sentence lifted out of the text and avoided those for which the answers were emphasized by special type or appeared in the end-of-chapter summary. Since the questions were listed in the order that the answers appeared in the text, the students were encouraged to answer them while they were reading. The following represent types of preview questions used on the assignments. Chemical Equilibrium The value of the equilibrium constant varies only with and not the initial o f the reactants and products. Acids and Bases What is the ionization equilihrium for the weak base hydroxylamine, H2NOH? Coordination Chemistry Four-coordinatecomplexes have two common geometries, -while six-coordinatecomplexes have an -and -geometry. The complementary color of red is ,Field Testing and Prelecture Assignments Each srudent n:crived a packet contatning the prelecture assignments at thc first clacs tnccting. It included n descriptim Volume 62
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of the purpose of the assignments and how to use them effectively. These ideas were also discussed in the opening lecture. The course syllabus indicated the date each assignment was due. Graded assignments were returned and a key was posted on the course bulletin board. The assignments were not mandatory, but extra credit points were awarded. It was possible for the students to improve their course grade by 6.590 if thev completed all the assianments correctlv. ~ u r i n the g semester, 81%i f the class turned in an assignment at anv one time. The table shows the results of a auestionnaire the students were asked to complete at the end of the semester. In addition t o the students finding the assignments a useful learning aid, they were also found helpfulfor stimulating class participation. It was easier to involve actively
510
Journal of Chemical Education
the students in solving the sample ~roblemssince thev had completed some of the math in-the review questions. They could also he asked to participate in the presentation of factual macerial that wns covered in the previbw questions. The assignments had an altitudinal effect as well. Stwrra1 students commented that hy providing them with the assignments it made the coune seem more student-oriented. Hecause t,f thtw added instructional advantages, I encourage other general chemistry teachers to consider incorporating the assignments in their courses.6
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A sample copy of a prelecture assignment will be provided by the author upon request.
