A Self-paced Course for the General Student
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by Elaine W. Ledbetter
For the past twenty-five years I have taught chemistry in P;3mpa Senior High School. Pampa, Texas has a population of some 25,000 and we have an average enrollment in grades 1c)-I2 of 1050 students. About 47% of our students go on to cc,Ilege. Two years of laboratory science are required for graduation. Most students take Physical Science and Biology. T he ~-~chemistrv enrollment fluctuates between ten and fifteen Pfm e n t of thk student population. We normally have two classes of accelerated chemistrv (Chem A) and three classes of Practical Chemistry. If. on the first dav of the term a teacher of physical educatitm'told his students that in order to pass the course they ould each have to clear a five-foot har, we would say he was ?ing unrealistic. A few might clear it on the first day and ntwer be challeneed apain; others might never clear i t no ago it occurred to m atter how hard they worked. A few m e that I was teaching chemistry in just this manner. I was u: iing one textbook for all students and setting one standard for all regardless of their backgrounds, their interests, or their nt?eds. Fiom this realization came the change in our curriculum which permits students a choice of the level at which they W ish to enter the study of chemistry. Students with a strong math background and high motiVLition in science elect to take Chem A. For this course I use thle Prentice-Hall version of the Chem Study program. I keep tl.le classes together in the traditional manner for two reasons: f irst, ~ a great deal of explanation and discussion is needed; second, many of the experiments are more meaningful when class results are pooled and trends can be analyzed. Mv greatest pleasure in teaching has come during the past w ;e&s since1 have designed a course for the general str ?nt. It presents the fundamental concepts in chemistry i ~~~~~
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Elaine W. Ledhetter is currently chairman of the Science Department and a chemistry teacher at Pampa Senior High School. She received her BS from the University of Oklahoma and her MEd from North Texas State University and taught in the Blackwell Oklahoma and Shidler-Webb City School systems before joining the staff at Pampa where she has taught since 1951. The author of two textbooks for high school students and many articles in national teaching Elaine W. Ledbetter iournals. Ms. Ledhetter has been honored many times for Pampa Senior High School Pampa. Texas her teaching and service to the educational community. Among these are the first James B. Conant Award for the Fifth District in 1967 and the Catalyst Award from the Manufacturing Chemists Assoeiation in 1977.She has served as an officer bf many local and national organizations including President of the Science Teachers Assoeiation of Texas, Memher of the Colleee Board Committee to write the Chem-
6 / Jovml of Chemical Education
a less rieorous. non-mathematical context; i t relates the importance of chemistry to the daily lives of students; it contains manv options in the form of minicourses; and it permits the stud&tto pace himself. Although students know from the first day that they will be planning their own schedule, I keep the classes together for the first two weeks or so. This enables me to instruct them in safetv orocedures. acouaint them with the names and uses of laboratory equipken;, introduce routine laboratory techniaues and assist them in distinauishina between activities that must he done within the classroom and those that should be done a t home. Deadlines for the completion of each unit of work are essential to the success of any self-pacing program. Otherwise, a few students would still be on Chapter 1 at the end of the year! I give each student a copy of the deadline schedule for the entire course. These are quite lenient and any student who manages his time with any degree of efficiency can meet them. However. there are built-in rewards as well as oenalties. -~tudents'whobeat any deadline earn bonus point; students who fail to meet anv deadline lose ~ o i n t on s a graduated scale depending on howiate their workis. Each unit of work has its own stated ohiectives and a suagested order of study so that students are b i d e d in what they should do and in what order. In most cases, laboratory work introduces the concepts and the textbook discussion focuse? on what they have seen and done in the laboratory. Laboratory management is not difficult in the self-pacing proaram. I have plastic tote trays for each experiment. These &e labeled with the experimentnumber and each one contains the special materials required for that experiment. In the beginning of the year it may be necessary to have more than one tote tray per experiment because the students are pretty well hunched at that time. However. after the first few weeks they become sufficiently scatteredso that only one tray is needed oer exoeriment. The first vear throuah such a p. r w. a m require; the most work in preparing the tote trays. After that it becomes a matter of simolv materials. l h i s . . re~lenishina . plan has another large advantage: one does not need as much equipment as when a class performs an experiment all at the same time. Fewer balances, graduated cylinders, gas tubes, etc. are reauired when only one or two students are using them simultaneously. One of the greatest rewards of self-pacing is the increased amount of time I have to spend with each individual student. This is particularly helpful in lab work. When a student completes an experiment I am able to go over his results with him while the materials are in front of him. He can ask questions and I can clarify the problems he may have encountered. This prevents his doing a report on misleading or erroneous results. Another interesting aspect of self-pacing is the amount of responsibility my students take in assisting one another. Some students are more comfortable about seeking the help of a peer than they are about seeking my help, and this is healthy. For when a student understands a concept well enough to explain it to another this is excellent reinforcement. Not only do the students help each other on lah problems, hut they tend to form small discussion groups to go over textbook material. I give credit for what I call Free Labs. These are experi-
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cards. The cards are color coded: white cards test laboratop. skills; green cards test math and/or forrnula- equation writing skills; hlue cards test data interpretation wrnnhs. tables. etc., pink cards test facts; orange lards test ihehigher s k h d application and understanding and contain multiple com pletion and assertion-reason questions. There are five card! of each color which have questions that are as nearly uaralle as possihle. The student draws one card of each rob; A d tha is his test. The lab card requires that he actually go into tht lah and perform a test that he has learned during that unit o work. Kxample: determine the density of an object h y an! method he chooses: determine the DHofa solution:.determint whether a given sdlid dissolves endothermically or exother. mically, etc. My tests are closed book, hut if a student make1 a grade of 85 or higher on his test he is permitted to draw ar honor card. These have questions that are much more difficull and in-depth. The student may use any hook in the room help him answer the question. He can earn extra grade ~ointr on these honor cards. If a student fails to make a passing grade on any test, he car review what he missed and retake the test as many times as is necessary for him to pass. However, if he must retake an) test. the hiehest .. made he can receive for that narticular tesl is 70. This means that anyone can pass if they are willing t, work, but it ~rovidesan incentive tu do well on the first at. tempt. students like this method of testing and consider il fair. I have been disturbed by the downward trend in chemist15 enrollment in this country. I am convinced that Dart of the reason is that we have been trying to teach colleg~chemistr~ to exploring high school students. The majority of these stu. dents simply want to know what chemistry deals with and how it is related to them now-where they are. They neither want nor need kinetics and solubility product constants a t this point. If we can offer them an exciting introductory course that seems relevant and meaningful to them, some will s u r e l ~ pursue the study further a t which time they will learn the sophisticated concepts because thev want to learn them. hose who do not c&e to continue the study of chemistry will be left with a happy and a better understanding -..experience . of the great importance of chemistry in every aspect of the;
ments the students design themselves. Plans for a Free Lab must he approved by me at least twenty-four hours prior to the period the student wishes to perform the experiment. This allows me tb check the proposal for safety and also to permit me to have the needed materials ready. In this way, I do not have to waste class time in the stockroom. A proposal for a Free Lab must have a stated hypothesis (or purpose or question-whichever is most appropriate), a list of materials needed, and a step-by-step plan of procedure. This assures that the student has thought his idea through thoroughly enough to be able to pursue his experiment with a t least some direction. I do not make suggestions on how a plan of attack might be improved, because I feel that students learn best by doing. In many, many cases a student will find as he proceeds that his plan was faulty. When this happens, he revises his own work and begins again. I t is extremely rewarding to watch the progress students make during the year in designing original laboratory work and to see how much pleasure they derive from it. Some outstanding Free Labs: determining the melting point of a solid (student learned how to make a melting tube), testing various brands of liphalm for moistness, determining the percent of water in different brands of canned corn, why bubbles arise from the same points in a beaker of boiling water, why popcorn pops-weight differences before and after popping, crystals and candy making, and the chromatography of food coloring. At a certain point in the course when students know about the states of matter, something about the kinds and properties of solutions, and have mastered the major characteristics of acids, bases, and salts, they are given the option of choosing from a variety of minicourses. Some of these are: Environmental Chemistry, Colloid Chemistry, Making Effective Decisions, The Chemistry of Over-the-counter Drugs, Soils and Fertilizers, Petroleum, Foods, Food Additives, Soaps, Detergents and Cosmetics. Students who opt to do minicourses have the opportunity to peruse those that are available. They then sign a contract stating which minicourses they plan to do and the due dates for completion of each. I normally allow six weeks for this phase of the course. These modules create tremendous interest and have proved t o be one of the most meaningful aspects of the course in relating chemistry to the lives of the students. I close the year with three weeks of elementary qualitative analysis. Most students consider this the real highlight of the course. They enjoy doing "unknowns" and it pulls together many of the principles they have learned. I t leaves them with a pleasant and satisfying experience which I consider most important. They do a series of "knowns" to acquaint them with the procedure and the normal results for certain tests. They are then expected to complete a minimum of five "unknowns." Extra credit is given for all above the minimum that are satisfactorily completed. The grade on any "unknown" is determined by the following: correct identification of the cation and the anion, ability to explain the chemistry of all positive tests, and ability to write the correctly balanced chemical equations for all positive tests. They are given a sheet with the grading scale on it at the beginning of the unit so they can aim for whatever grade they wish. In this way grading is more objective and students know exactly what is expected of them to earn a grade in each category. And now a word about evaluation. The six-weeks grade is determined by grades on experiment reports, free labs, outside reading, creative work (posters, bulletin boards, etc.) and tests. The test for each chapter consists of a deck of twenty-five
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This alternative may he threatening to die-hard chemistry teachers who want their course to he known as the most difficult in the school curriculum. I contend that we need at least two levels of chemistry in our high schools: one for the young and talented potential scientist and one for the general population. Surely the latter group is in the majority and it is this c r o u ~who will become the maior block of votine citizens of iom&row. To make intelligent iecisions about enkonmental issues, enerw ... SUDU~Y. . . . drug use and abuse. as well as ~ersonal decisions ahmu heing a wi
