Get Complete Information About the Grades System
The discussion of the evaluation of results of teaching and learning is incomplete without a consideration of the real importance of test scores once they have been obtained.
However, teachers and students must not consider evaluation solely as a means of obtaining grades. Basically, there are but two grading systems in use at present in this country. All other types of grading system are variations of these two.
The first of these is called the Grade Plan or the Percentage System; the other, the Missouri Plan or the Normal-Curve System.
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1. The Garrett Plan or the Percentage System
The percentage system of grading assumes an absolute standard. The grades have some subjective concept of perfect performance for the particular exercise being graded. To this perfection standard he assigns the value of 100 per cent or 100-point scale. The exercise is then judged against this 100 per cent standard.
This system is applied to examinations, test, and any other means used to measure the results of teaching and learning.
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If the outcome of the examination or test shows that three-fourths of the quantity or quality of the perfect exercise is covered satisfactorily, it is given a grade of 75 per cent; if it reaches nine-tenths of the way towards the perfection goal, it is assigned a grade of 90 per cent.
The percentage system is used in all public elementary and secondary schools and some private school, college, and universities in the Philippines. The University of Santo Tomas and Far Eastern University use this system of grading.
As noted in the preceding illustration, the percentage system assumes a range of grades from 0 to 100: In other words, it is assumed that a teacher is able to distinguish 101 levels of achievement or ability. Psychology tells us, however, that the human mind; in rarely able distinguish more than five to seven classes in any situation.
We would all probably confirm this idea if we had experience in grading test papers.
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Those who advocate the curve system for grading purposes take cognizance of this fact inasmuch as they recommend that somewhere between three and seven grade distinction should be made.
A second serious mathematical formula that would apply to this situation is wherein a relatively small proportion of a class will receive grades scattered all along the way from 0 to 70, let us, say, and the much larger section of the class receives grades in the relatively smaller range of 30 points, from 70 to 100.
2. The Missouri Plan or the Letter-System based on Normal- Curve
The letters-system based on Normal-curve uses an entirely different point of reference. It is a system of distributing grades based on the normal probability formula and the law of chance.
The average achievement or ability of the particular class taking the test is used as a standard against which each individual’s performance of judged.
The individual’s test performance is graded in proportion to its distance from the average score. The group of scores clustering around the average score is given the middle grade symbol; the scores better than the average, another symbol; those lower than the average, another symbol; and so on out as far as the particular school system demands.
This plan is based upon relative values, and marks are determined according to the rank or order of the merit. The distribution of grade is determined by some arbitrary scheme, such as the normal curve or some percentage distribution.
Grades under such conditions are usually in letters or numbers, and the scales ordinarily used have four or five divisions. The University of the Philippines and Silliman University use this system of grading.
The real difference between these two systems is that the Percentage or Garrett Plan assumes that the standard of judgment can be applied reliably and validly by the teacher, while the Normal- Curve or Missouri Plan recognized that test vary in difficulty and that judgments vary in the marking; hence, marks can and should show relative ability only.
According to Ruche “marks cannot be reduced into an absolute scale such as the percentage scale because no one knows what 100% means.” However, reducing relative marks into percentage still persists in the Philippines and in America.
The normal-curve system, on the other hand, originates from the basic mathematical laws of chance, and is constructed according to the binomial expansion theorem. With such mathematical precision, one can face the grading problem with greater confidence that the results will be reliable.
A marking system based upon the normal probability curve indicated by the five letters with their corresponding areas computed on the basis of the M (median) and 6 (S.D.).
In a five-letter system based upon M and 6 or S.D., the areas representing the various letters are described as follows:
I. A is 1.50 or more above the Mean.
II. B is between +.50 and +1.50,
III. C is between -.05 and +.50,
IV. D is between-, 50 and -1.50.
V. E is 1.50 or more below the Mean.
The normal-curve pictures accurately what actually happens when a large, unselected group is measured for educational achievement and the results are presented graphically. Since this is what happens under controlled conditions, it gives us a guide as to what we might expect in a particular testing situation; hence, it might be called the expectancy curve.
When the results of the particular test that we administer do not take the form of the curve, we are challenged to answer the question “Why?” Has the instruction been faulty? Has the test been properly constructed? Has the subject-matter been too easy or too hard? Just what has happened?