Abstract:
The specification discloses a hand-held calculator of the type used by teachers in averaging grades. The calculator permits intermixed entry of letter grades and numeric grades in an averaging sequence. A weight table may be stored in the calculator for automatic nonlinear weighting of inputted grades in the averaging process. An excused absence key permits a data entry that will not affect the average of the other inputted grades. The calculator permits display in any one of a variety of modes, such as letter grade, percent, and total points.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to electronic hand-held calculators and more specifically to electronic hand-held calculators for processing student grades. 
     A variety of electronic calculators capable of processing student grades have been developed. These calculators facilitate the processing of student grades that are in either numerical or letter format. 
     A series of unique and clever grade averaging calculators have been patented by the present inventor. One such calculator is disclosed in U.S. Pat. No. 4,048,484, issued Sep. 13, 1977, and entitled DlGITAL GRADE AVERAGER. This calculator operates in either standard calculator mode or grade averaging mode. The grade averaging mode processes only letter grades. 
     A second such calculator is disclosed in U.S. Pat. No. 4,715,011, issued Dec. 22, 1987, entitled GRADE AVERAGING CALCULATOR. This calculator operates in three different modes: numerical grade mode, letter grade mode, and timer mode. The user selects the desired mode by depressing the appropriate key. Although this invention is a notable advance in grade averaging calculators, it requires letter and numerical scores to be processed in separate mutually exclusive modes. 
     SUMMARY OF THE INVENTION 
     In a first aspect of the invention, a calculator is provided capable of simultaneous mixed processing of both numerical and letter grades. More particularly, the calculator includes a matrix of keys for inputting both numerical and letter grades, means for converting the letter grades to numerical grades, and means for processing a series of numeric values to produce a numerical average. The calculator assigns a numeric value to a letter grade as the median of the range of scores assigned to that letter grade. 
     In a second aspect of the invention, the calculator accommodates &#34;excused absences&#34; or &#34;no grades&#34; that result from missed tests. More particularly, the calculator includes a means for incrementing the number of grades inputted while not adversely affecting the grade processing. 
     In a third aspect of the invention, the calculator is capable of converting and displaying the averaged grades among a series of grading systems. More particularly, the calculator includes a means for converting output to one of a series of grading systems, a means for displaying that output, and a means for allowing the user to select the desired grading system display. 
     These and other objects, advantages, and features of the present invention will be more fully understood and appreciated by reference to the detailed description of the preferred embodiment and the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a flow chart illustrating the flow of the &#34;main&#34; routine of the calculator; 
     FIG. 2 is a flow chart illustrating the flow of the &#34;numerical grades&#34; subroutine; 
     FIG. 3 is a flow chart illustrating the flow of the &#34;letter grades&#34; subroutine; 
     FIG. 4 is a flow chart illustrating the flow of the &#34;subtotal average&#34; subroutine; 
     FIG. 5 is a flow chart illustrating the flow of the &#34;student average&#34; subroutine; 
     FIG. 6 front view of the calculator of the present invention; and 
     FIG. 7 is a block diagram of the calculator. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A calculator constructed in accordance with a preferred aspect of the invention is illustrated in FIG. 6 and generally designated 10. The calculator includes a body or housing 12 supporting a keypad 13 and a display 14. The display includes a number section 16, a numerical display section 18, a letter grade section 20, and a plurality of annunciator/indicators. The calculator 10 is illustrated in block form in FIG. 7 in a configuration that is conventional in the art. Specifically, the keypad 13 and the display 14 are both connected to a processor 15. A storage device 17 is also connected tot he processor 15. The processing and/or conversion functions described in this application are carried out by the processor 15; and storage functions are accommodated in storage device 17. 
     The keys supported within the body of the calculator are as follows: 
     
         ______________________________________               DesignatingKey                 Numeral______________________________________ON/CE/C             22SET                 24WHOLE GRADE ONLY    26GRADE SCALE         28OFF                 30GRADE DISPLAY       32ENTER NUMBER GRADE  34Individual Letter Grades               36STUDENT AVERAGE     38SUBTOTAL AVERAGE    40MAXIMUM POINTS      42MINIMUM POINTS      44Individual Numbers  46%                   48CLASS AVERAGE       50M+                  52M[R/C]              54/                   56×             58+                   60-                   62·          64=                   66NO GRADE            68WEIGHT              70______________________________________ 
    
     The function of these keys is explained in conjunction with the flow charts of FIGS. 1-5. 
     Internally, the calculator includes a weight table that will store the weight of up to seven grades. The weight table is used to accommodate test scores that are of varying importance. For example, the user may program the calculator to make a final exam worth five times the weight of a weekly quiz. By appropriately adjusting the weight table, the user can cause the calculator to automatically process the grades accordingly. 
     To adjust the weight table the SET 24 and WEIGHT 70 keys must be depressed in succession. The first entry in the weight table will be displayed by the calculator. To traverse through the table the SET key 24 must be depressed. An individual entry can be adjusted by entering the desired weight before depressing the SET key 24. Each entry in the weight table has a default setting of one, thereby assigning each grade equal value unless modified by the user. 
     Also internally, the calculator includes a break point table. This table is used to store the break points between the individual letter grades. Each letter grade is assigned a numerical break point that represents the lowest numerical score that will achieve that particular letter grade. By reference to this table, the calculator can easily convert between letter and numerical grades. 
     The default setting of this table is based on a hundred point scale with one hundred being the maximum points and sixty being the minimum points (Table 1). The break points are derived by dividing the range defined by the high and low score into four subranges. These subranges define the whole grade break points. For example, the default whole grade break points are: 90 for an A, 80 for a B, 70 for a C, and 60 for a D. The subranges are further divided into three segments. These segments define the signed grade break points. For example, the signed grade break points for an A become: 96.66 for an A+, 93.33 for an A, and 90.00 for an A-. 
     
                       TABLE 1______________________________________Letter Grade   Break Point______________________________________A+             96.6A              93.3A-             90.0B+             86.6B              83.3B-             80.0C+             76.6C              73.3C-             70.0D+             66.6D              63.3D-             60.0______________________________________ 
    
     Although these break points are permanently embodied in read-only memory (ROM), the user can edit them to implement his own linear or non-linear scale using the nonvolatile area of random-access memory (RAM) by incorporating the SET 24 and GRADE SCALE 28 keys or the SET 24 and seven (7) keys 46. The SET 24 and GRADE SCALE 28 keys are used to edit only the whole grade break points. When depressed, the calculator will display a whole grade and its corresponding break point. If that break point requires adjustment, the desired break point is entered followed by depression of the SET key 24. This stores the new break point and displays the next default whole grade break point for editing. To store the next displayed default break point without adjusting the displayed break point, only the SET key 24 should be depressed. 
     The calculator automatically separates the whole grade ranges into three equal segments. These segments represent the signed grade ranges. For example, if the whole grade break point for an A is 92 and the whole grade break point for a B is 80, the signed grade break points become: 80 for a B-, 84 for a B, and 88 for a B+. The signed grade break points can be adjusted in a manner identical to one discussed immediately above, except that the SET 24 and seven (7) 46 keys should be depressed rather than the SET 24 and GRADE SCALE 28 keys. The user-implemented Break Points Table constitutes a second separate table from the default Break Points Table. 
     In addition, if the user alters either the maximum points (default 100 ) or minimum points (default 60), the calculator creates a third break point table to reflect that change. The new break points are computed in such a manner that the new grade ranges are proportionately equal to the user break point table, if implemented, or the default break point table. The following formula is used to convert the break points to the new break points of the third scale: ##EQU1## 
     I. MAIN ROUTINE 
     Program flow of the main routine 100 is illustrated in FIG. 1. The calculator is powered on by depressing the ON/CE/C key 22. Likewise, the calculator is powered off by depressing the OFF key 30. The weight table is reset to the default values, and the MAX and MIN values are reset to the (a) user defined values, if implemented, or (b) the default values (100, 60) each time the calculator is powered on. However, the user-defined break point table containing any modified break points is not reset to default, and the display format is not reset, unless the batteries are removed or the user performs a hard reset. A hard reset is performed by depressing the SET key 24 immediately followed by the times (X) 58 key. The main routine 100 will process letter grades, numerical grades, or standard calculator functions. In order to facilitate a precise description of the operation of the calculator, the following internal variables will be used: 
     
         ______________________________________Variable    Description______________________________________MAXPTS      Maximum points achievable on a testMINPTS      Minimum points acceptable on a testWTTOT       Individual student weight factor totalGPTOT       Individual student grade point totalAVE         Individual student grade point averageGD-PTS      Current grades total grade points (after       weighting)WF          Weight factor (internal table)NO-GDS      Individual student number of gradesNO-ST       Number of students processedCL-PTS      Summation of the grade points earned by       each studentNUM         Numerical representation of the current       gradeLET-GR      Letter grade corresponding with to cur-       rent grade______________________________________ 
    
     II. NUMERICAL GRADE ENTRY 
     The main routine 100 transfers control to the numerical grade subroutine 200 when the ENTER NUMBER GRADE key 34 is depressed. This subroutine processes the number stored in the key register. If the key register does not contain a number the control is immediately returned to the main program 209. 
     The calculator permits the entry of numeric grades or points off/negative grading. To accommodate the negative grading aspect of this invention, the subroutine compares the number in the key register to zero 205. If the number entered was negative, then that number is subtracted from MAXPTS to produce the corresponding grade point score 208. If the number in the key register is not negative then that number is determined to be the grade point score. At this point, the calculator weights the grade point score by multiplying the grade point score by the appropriate weight factor 206. This product is the current grade&#39;s total grade points, GD-PTS. The appropriate weight factor is either retrieved from the weight table or manually entered. 
     An individual student&#39;s first seven grades will automatically be weighted according to the internal weight table. However, the weight factor of a single entry can be altered by inputting the desired weight factor and depressing the WEIGHT key. This feature also allows the user to weight grades beyond the seven entries in the weight table. 
     The numerical grade subroutine 201 processes the grades by storing a summation of the current student&#39;s weight factors in WTTOT and total grade points in GPTOT 206. The subroutine also stores the number of grades entered for the current student in NO-GDS 206. These summations are retained until the STUDENT AVERAGE key 38 or OFF key 30 is depressed. The subroutine displays the number of grades for the current student, the current grade&#39;s numerical score, and the current grade&#39;s letter score 206. Finally, control is returned to the calling routine 211. 
     III. LETTER GRADE ENTRY 
     The main routine 100 transfers control to the letter grade subroutine 301 when any of the letter grade keys are depressed. This subroutine utilizes the internal break point table to convert each letter grade to a numerical grade. The break point for the current letter grade and the break point for the next highest grade are retrieved from this table 302. If the current letter grade is the highest grade achievable, MAXPTS is deemed to be the upper break point. The subroutine computes the median of these two scores by summing them and then dividing this sum by two 302. This median score is treated as the numerical grade representation of the letter grade and is processed by the numerical grade subroutine 303. 
     IV. NO GRADE ENTRY 
     In a preferred embodiment of the present calculator a means for processing a missing grade is included. The NO GRADE key 68 allows a user to advance through the weight table in the event that a particular grade is missing. Upon depression of the NO GRADE key 68, the main routine 100 simply increments NO-GDS 114. Grade weights are retrieved from the internal weight table using NO-GDS as an index. Therefore, incrementing NO-GDS results in skipping an entry in the weight table. 
     V. OUTPUT 
     The calculator will display the student&#39;s subtotal average, the student&#39;s final average, and the class average. 
     VI. SUBTOTAL AVERAGE 
     The main routine 100 transfers control to the subtotal average subroutine 400 when the SUBTOTAL AVERAGE key 40 is depressed. This subroutine will display the current student&#39;s average numerical grade, average letter grade, and number of grades entered 403. This subroutine differs from the student average subroutine in that it does not signal the end of the current student&#39;s processing. Therefore, subsequently entered grades are processed as a continuation of the previously entered grades. 
     Depressing the SUBTOTAL AVERAGE key 40 also has the effect of depressing the ENTER NUMBER GRADE key 34. Immediately upon entering the subtotal average routine 401, control is temporarily passed to the numerical grade subroutine 200. If the key register is not empty its contents will be processed and included in the current output. In any case, control returns to the subtotal average subroutine 400. 
     After return from the numerical grade subroutine 200, the calculator displays the number of grades processed for the current student, NO-GDS; the average numerical grade, GPTOT divided by WTTOT; and the average letter grade, retrieved from the internal break point table based on the average numerical grade 403. Immediately following display, control is returned to the calling program 404. 
     VII. STUDENT AVERAGE 
     The student average subroutine 500 performs several functions. First, it indicates that the last grade for the current student has been entered. Secondly, it maintains the class average variables. And finally, it displays the current student&#39;s total number of grades, average numerical score, and average letter score. 
     The student average subroutine 500 is called by the main routine 100 when the STUDENT AVERAGE key 38 is depressed. The student average subroutine 500 transfers control to the subtotal average subroutine 400. The subtotal average subroutine 400 processes any grade in the key register, displays the proper output 403, and then returns control to the student average subroutine 404. 
     Subsequently, the student average subroutine 500 maintains the class average variables. NO-ST is incremented to reflect the number of students in the class 503. The student average, or GPTOT divided by WTTOT, is added to CL-PTS to facilitate later calculation of the class average 503. Lastly, the current student variables are cleared; GPTOT, WTTOT, and NOGDS 503. 
     VIII. CLASS AVERAGE 
     The class average subroutine is called by the main routine 100 when the CLASS AVERAGE key 50 is depressed. This subroutine displays the total number of students processed, the average numerical grade, and the average letter grade of those students. The number of students processed is stored in the variable NO-ST. The numerical grade average is calculated by dividing CL-PTS by NO-ST and the letter grade average is retrieved from the internal break point table. 
     IX. DISPLAY FORMATS 
     The calculator accommodates the following grading systems: raw score (&#34;PTS&#34;), 4 point (&#34;4&#34;), 5 point (&#34;5&#34;), 12 point (&#34;12&#34;), percent (&#34;%&#34;), and scaled grade percent (&#34;G%&#34;). The user selects the appropriate display format by repeatedly depressing the GRADE DISPLAY key 32 to cycle through the stated display formats. The current display format is identified by one of a series of annunciators present in the display window. Internally, the calculator processes grades based on a raw score. Therefore, unless raw score format has been selected, the grade must be converted prior to display. 
     The conversion between grading systems is achieved by the following algorithms: 
     Raw score to percent: ##EQU2## 
     Raw score to scaled percent: ##EQU3## 
     Raw score to 12 point: ##EQU4## 
     12 point to 4 point: ##EQU5## 
     4 point to 5 point: 
     
         G.P..sub.5 =G.P..sub.4 +1 
    
     In addition, the following foreign grading systems can be incorporated into the calculator based on the following algorithms: 
     12 point to 10 point (Japan): 
     
         G. P..sub.10 =G. P..sub.12 -2 
    
     
         G. P..sub.10 =G. P..sub.4 +6 
    
     5 point to 1 point (Germany): 
     
         G. P..sub.1 =6-G. P..sub.5 
    
     X. OPERATION 
     The present calculator quickly and easily processes student grades in either numerical or letter format. The calculator is powered on by depressing the ON/CE/C key 22. The weight table is reset to default automatically, and the student and class counters are cleared. 
     As example 1, a maximum score of 100 and minimum score of 60 establish the break points listed above in Table 1. The entry of the following scores results in the following display: 
     
                       TABLE 2______________________________________NumberofGrades    %       G %    4    5    12   PTS   LTR______________________________________86   1        86      86   3.10 4.10 9.3  86    BA    2        95      95   4    5    12   95    A-25  3        75      75   2    3    6    75    C74   4        74      74   2    3    6    74    C-39  5        61      61   0.6  1.6  1.8  61    D-B+   6        88.33   88.33                      3.33 4.33 10   88.33 B+Avg  6        79.88   79.88                      2.49 3.49 7.47 79.88 C+______________________________________ 
    
     All grades are converted to numeric form before processing. Once processed, the numeric scores are converted to the desired display format. 
     As example 2, a test having a maximum score of 65 and a minimum acceptable score of 25 results in the following break points and illustrates the scaling up of the grade from true % (A-=87.18%) to grade % (A-=91.67 G %) due to the fact that minimum points is below 60% (the default scale minimum %): 
     
                       TABLE 3______________________________________Letter Grade   Break Point______________________________________A+             61.6A              58.3A-             55.0B+             51.6B              48.3B-             45.0C+             41.6C              38.3C-             35.0D+             31.6D              28.3D-             25.0______________________________________ 
    
     And, accordingly, the entry of the following individual scores yields the following display: 
     
                       TABLE 4______________________________________    %    G %    4      5    12   PTS  Letter______________________________________A-       1     87.18  91.67                      3.67 4.67 11   56.67                                          A--12      2     81.53  88.00                      3.30 4.30 9.90 53.00                                          B+39       3     60.00  74.00                      1.90 2.90 5.70 39.00                                          CNo Grade 4C+       5     66.66  78.33                      2.33 3.33 7.00 43.33                                          C+Avg      5     73.84  83.00                      2.80 3.80 8.40 48.00                                          B-______________________________________ 
    
     In example 3, the user has offered 4 tests, each of varying weight: 
     
                       TABLE 5______________________________________   Quiz 1 1   Midterm          2   Quiz 2 1   Final  4______________________________________ 
    
     To automatically process the grades based upon the above-listed weights, the user depresses the SET key 24 and WT key 70 in succession. Next, each weight is individually entered, followed by depression of the SET key 24. Once the weights are entered, the calculator automatically weights the corresponding grades. The following table demonstrates the processing of weighted grades based on maximum points=100 and minimum points =60. 
     
                       TABLE 6______________________________________(MAX PTS = 100 and MIN PTS = 60)NumberofGrades    %       G %    4    5    12   PTS  LTR______________________________________B+   1        88.33   88.33                      3.33 4.33 10.00                                     88.33                                          B+C-   2        71.67   71.67                      1.67 2.67 5.00 71.67                                          C--15  3        85.00   85.00                      3.00 4.00 9.00 85 00                                          B98   4        98.00   98.00                      4.30 5.30 12.90                                     98.00                                          A+Avg  4        88.58   88.58                      3.36 4.36 10.08                                     88.58                                          B+______________________________________ 
    
     Table 7 demonstrates the use of the NO GRADE key 68 in conjunction with the internal weight table described in Table 5. 
     Once again, Maximum points=100 and minimum points=60: 
     
                       TABLE 7______________________________________(MAX PTS = 100 and MIN PTS = 60)NumberofGrades      %      G %    4    5    12   PTS  LTR______________________________________B+     1        88.33  88.33                       3.33 4.33 10.00                                      88.33                                           B+No     2Grade-15    3        85.00  85.00                       3.00 4.00 9.00 85 00                                           B98     4        98.00  98.00                       4.30 5.30 12.90                                      98.00                                           A+Avg    4        94.22  94.22                       3.92 4.92 11.77                                      94.22                                           A______________________________________ 
    
     As example 4, a negative grading model is demonstrated. A 5-page test has been graded by determining the points off per page. To automatically compute the total points off and process this score, the user simply depresses the minus (-) key 62 followed by the points off for each page. After entry of the final page&#39;s points off, the ENTER NUMBER GRADE key 34 is depressed to process the test score. The following table demonstrates points off grading and its appropriate displays. The maximum points=100 and minimum points=60: 
     
                                           TABLE 8__________________________________________________________________________(MAX PTS = 100 and MIN PTS = 60)Points off       Total                % G %                     4  6  12 PTS                                 LTR__________________________________________________________________________-3,   -2, -5,    -1,       -0 1 -11 89                  89 3.4                        4.4                           10.2                              89 B+-7,   -6, -5,    -8,       -1 2 -27 73                  73 1.8                        2.8                           5.4                              73 C--1,   -0, -0,    -2,       -1 3  -4 96                  96 4.10                        5.10                           12.30                              96 A-9,   -13, -4,    -8,       -4 4 -38 62                  62 0.7                        1.7                           2.10                              62 D-__________________________________________________________________________ 
    
     XI. CONCLUSION 
     The above description is that of a preferred embodiment of the invention. Various changes and alterations can be made without departing from the spirit and broader aspects of the invention as set forth in the appended claims, which are to be interpreted in accordance with the principles of patent law, including the doctrine of equivalents.