John F. Garst The Universitv of Georgia
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Grade Analysis with a Programmable Electronic Calculator
Proerammable nocket electronic calculators (PPECs) are ~" getting better a n d cheaper rapidly. T o a chemistry teacher, they offer a t least two opportunities, that of enrichment of chemistry courses and that of increased efficiency of grade analvsis. I have found it uerv convenient to use a PPEC in my chemistry class of -70 st"grade analysis for a dents. Some surprisingly complex calculations can be programmed in 49 program steps (the least capacity available in a commercial PPEC) or less, and the advantages of a PPEC over conversational calculations at a terminal, batch processing with a digital computer, and even calculations with a programmable desk-top calculator can be significant. Some of the eood features and advantaees of a PPEC follow: (1) sufficient programming power for all cut the most complex grade analyses; (2) low cost; under $200 to about $800; (3) simplicity; programming is almost the same as a manual calculation: (4) reliabilitv: little if anv "down time:" (5) immediate accei$ihility; we; i t or keepit in your desk; (6)speed; time for enterine a 49-sten. Droeram is about 2 rnin: some . program storage on magnetiecards; PPECs have (7) ~ortabilitv: . . meat " .. and (8) verv small size. The last two features add up to real convenienre, since one can take his test papers and his I'PEC and plunk them down on some larye table and do integrated marking and calculating. PPECs provide two opportunities in grade analysis: time savings and increased flexibility of grade analysis. T o exemplify what can be done, here are some examples from my own exnerience. Simple weighted averaging (3-hour tests worth 45% of the final -erade:. a laboratow. -. 20%:. a final examination. 35%) was programmed in 17 steps. A time savings of 12 min was esti-
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114 1 Journal of ChemicalEducaiion
mated for 70 students, and 1hr for 350 students, compared to times required for the same calculations using a manual pocket electronic calculator. Linear adjustment of raw scores (adjusted grade = m X raw score b) controls the spread and average of a grade set independently without changing the ratios of differences between grades. A 5-step program resulted in a 10-min savings for 70 students and 1hr for 350. Automated computation can be integrated with marking and aueraging. After each paper is marked, the number missed is keyed into the PPEC, which gives the raw score by subtraction. then the percent correct. At the same time the I'I'EC arcukulates a;tomatically the data needed for the comnutation of the mean and standard deviation therefrom. ~ h e i can e be obtained (for the papers already graded) by one-button manual operations a t any time, without upsetting the automatic (programmed) functioning of the PPEC. A 10-step program is sufficient. While the time savings are consid&&l~the major advantage is increased accuracy of the computations, compared to manual calculations of a similar nature. ~ ~ ~ Final grades can be computed by seueral methods with the PPEC choosine the one that counts. For example, I often permit the final examination tn weigh 50% or 25% whichever eives the student the better final averaee. Hv taking advantage of their conditional branching statements, PPECS can be programmed to make such choices automatically. A 27-step program saves 42 min for 70 students and 3.5 hr for 350 for the variable-final-exam-weight problem. Other fairly complex Ghekes could he programmed for a PPEC. I believe that the ready availability of these calculators signals a new era in the ease and flexibility of grade processing.
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