US 4,355,984 AGrant
Teaching Device
Issue Date:1982-10-26
•24 Claims
•3 Drawing Sheets
Abstract
A teaching device includes a reading station provided with six on-off switches for automatically sensing a text key encoded as a pattern of punched holes in a text book. The teaching device automatically generates an answer key from the text key by means of a pseudo-random number generator which is run using the text key as a seed. The text book includes a number of multiple choice questions in which the correct answer corresponds to the answer designated in the answer key.
Metadata
Assignee
- Nuvatec, Inc.
Inventors
- William H. Slavik
- William P. Carlson
- Michael J. McGowan
Application Information
Application Number:US 1338501
Filing Date:1980-03-25
Priority Date:1980-03-25
Art Unit:211
Classifications
IPC:
G09B 702G09B 706
Field of Search:
434322;323;335;353;354;356;357;358;359;362
Patent Drawings (3 sheets)
Description
Background of the Invention
The present invention relates to improvements in teaching devices of the type which evaluate multiple choice questions to aid self instruction.
The advantages of interactive teaching devices are well recognized. One class of these devices provides a number of multiple choice questions to be answered by the user as he proceeds through a course of study. Generally, the course of study will include textual material as well as a number of multiple choice questions. By answering the questions and then checking his answers, the user can check his level of comprehension.
Summary of the Invention
The present invention is directed to an improved teaching device which automatically determines the accuracy of proposed answers to multiple choice questions.
According to one feature of this invention, a teaching device is provided with means for automatically sensing an encoded text key associated with the text book in use, as well as means for automatically generating an answer key in response to the text key. This answer key provides a sequence of correct answers, which sequence is used in determining whether proposed answers selected by the user are correct. The invention is also directed to a text book having an encoded text key for use with such a teaching device. In the presently preferred embodiment, the text key is encoded as a pattern of perforated and unperforated regions arranged along a strip on one margin of one of the pages of the text. In this way, the teaching device can be easily programmed to recognize the correct answers for each separate text with a minimum of user intervention.
According to a second feature of the invention, the teaching device includes means for registering a text key and means for automatically performing a calculation based on the text key to generate an answer key indicative of a sequence of correct answers. In the presently preferred embodiment, the text key is supplied as a seed to a pseudo-random number generator. In this way, a relatively short text key can be used to generate a large number of potentially infinite series of randomly distributed correct answers. For example, a simple six bit binary text key can specify 64 different answer keys, each of which is independent from the others, apparently random, and of whatever length desired. Furthermore, this approach minimizes requirements for computer memory, since it requires much less memory to store a program for a pseudo-random number generator ("PRNG") than it does to store all the answer keys that can be generated with that PRNG.
The invention, together with further objects and attendant advantages, will be best understood by reference to the following detailed description taken in connection with the accompanying drawings.
Brief Description of the Drawings
FIG. 1 is a perspective view of a presently preferred embodiment of the present invention.
FIG. 2 is a detailed view of a portion of the text book shown in FIG. 1.
FIG. 3 is a cross sectional view taken along line 3--3 of FIG. 1.
FIG. 4 is block diagram of the electronic circuitry of the embodiment of FIG. 1.
FIG. 5 is a detailed schematic diagram of a portion of the circuitry shown in FIG. 4.
FIG. 6 is a partial top view of the embodiment of FIG. 1.
Detailed Description of a Presently Preferred Embodiment
Referring now to the drawings, FIG. 1 shows a perspective view of a presently preferred embodiment of the invention. This embodiment includes a binder 10 having a front cover 12, a back cover 14, and a spine section 16. The covers 12, 14 are flexibly mounted to the spine section 16 to allow the binder to fold up from the open position shown in FIG. 1 to a closed position (not shown) in which the front cover 12 extends over and generally parallel to the back cover 14.
Attached to the back cover 14 is a self-teaching module 40 which includes a keyboard 42, a digital display 44, and a text key reading station 46. The reading station 46 is adapted to receive a portion of a text book 20 and to automatically sense a six-bit digital text key encoded thereon. The structure and operation of the reading station 46 will be described in detail below in connection with FIG. 3.
FIG. 1 shows a text 20 positioned with a portion 24 of the text 20 in the reading station 46, ready for use. When not in use, the text 20 can be readily disengaged from the reading station 46, closed, and stored in a pocket (not shown) provided on the inside of the front cover 12. Then the binder 10 can be closed and easily carried or stored, like an ordinary binder.
Preferably, the text book 20 contains study materials as well as a number of multiple choice questions intersperced with the text. As used herein the term "multiple choice question" is to be understood as including true-false questions. Each question is followed by a number of possible answers. If a question is a true-false question then of course there are two possible answers. If the question is a multiple choice question, then five possible answers are provided.
FIG. 2 shows a plan view of a portion of the back page 22 of the text book 20. As used herein, the term "text book" is used to include books, booklets, leaflets, and single page structures which include a number of multiple choice questions, whether or not in conjunction with study materials; such study materials may include printed matter, audio recordings and visual recordings. The term "page" is meant to include covers as well as pages, whether or not thicker or less flexible than pages.
The back page 22 includes a flap 24 extending along the outer marginal edge. This flap 24 is connected to the page 22 at a fold line 30 and is foldable between a retracted position, in which the flap 24 does not extend substantially beyond the remaining pages of the text book 20, and an extended position, in which the flap 24 extends as shown in FIG. 2. In this embodiment, the fold line 30 is positioned to substantially coincide with the outer edges of the remaining pages (not shown in FIG. 2).
The flap 24 is provided with two registration holes 26, one at either end of the flap 24. These registration holes 26 are used to precisely align the flap 24 in the reading station 46. The flap 24 is also provided with a set of six digital indicia 27, 29 which encode the text key, a six bit binary number. In this embodiment, these indicia include perforated regions 27 and unperforated regions 29, which in combination encode the six binary number. By altering the pattern of perforations, the indicia 27, 29 can be made to encode any binary number between zero and 63 (decimal).
FIG. 3 shows a cross-sectional view of the reading station 46, showing the flap 24 in place. The reading station 46 includes a lower housing 52 and a hinged cover 48. The cover 48 is mounted to rotate with respect to the lower housing 52 about an axis parallel to the fold line 30 of the flap 24. The cover 48 moves between an open position (not shown) in which the flap 24 can be inserted in or removed from the reading station 46 and a closed position (shown in FIG. 3) in which the flap 24 is firmly held in position. Two registration pins 50 are mounted on the lower housing 52 to pass through the registration holes 26 in the flap 24, and thereby to align the flap 24 precisely in the reading station.
In addition, six mechanical on/off switches 54 are mounted on the lower housing 52, positioned to sense the presence or absence of perforated regions 27 in the flap 24. The cover 48 includes a number of ribs 56 positioned to press the flap 24 toward the lower housing 52 between the switches 54. As shown in FIG. 3, four of the switches 54 extend through perforated regions 27 while two of the switches 54 are depressed by unperforated regions 29 pressed against the switches 54 by the ribs 56. These switches 54 physically sense the six-bit text key encoded in the physical pattern of the digital indicia 27, 29 and generate in response thereto a digital pattern of switch closures. As will be explained below, this pattern of switch closures in turn generates a text signal which is used by the teaching module.
The presently preferred embodiment utilizes mechanical switches 54 to sense the text key. Those skilled in the art will recognize that other means can be used to record and automatically sense the text key. For example, the text key can be encoded as an optical pattern of either light and dark regions or translucent and opaque regions, and the reading station can employ light sources and photo-diodes or photo-transistors to sense the optical pattern. Alternately, the text key can be encoded and sensed magnetically. Of course, the length of the text key can be readily chosen to provide the desired number of distinct text keys. In addition, the text key can be placed at other positions on the text book 20.
Turning now to FIG. 4, the major electronic components of this embodiment include a microcomputer 80 which receives input signals from a switch matrix 100 and supplies output signals to drive a digital display 120, the switch matrix 100, and a speaker 140. A power supply 160 supplies a DC voltage at +5 volts to power the microcomputer 80 and other logic chips as well as a DC voltage at +30 volts to power the display 120.
In this embodiment, the microcomputer 80 is an AIM-65 including 4 kilobytes of Ramdom Access Memory, ("RAM"), marketed by Rockwell International. The program for the microcomputer 80 is shown in assembly language in Table 1, and its operation is discussed below. The digital display 120 is preferably an eight-digit, vacuum type seven-segment fluorescent display marketed by Futaba as type number 9-ST11. The microcomputer 80 selects which of the seven segments are to be illuminated in an individual digit via an 8 bit segment output bus 82 which is connected via a display driver 84 to the display 120. The individual digit being addressed is selected by the microprocessor 80 via output line 86 which is applied as an input to a three-bit counter 88 in order to step the counter 88 repetitively from zero to seven. Output signals from the counter 88 are applied to a 1-of-8 decoder 90, which then applies a signal to one of eight lines in control bus 92, depending on the number encoded in the output signals of the counter 88. In this way, the microcomputer 80 can sequentially address each of the eight digits in the display 120 via driver 85. In this preferred embodiment, the microcomputer 80 is programmed to step through the display at a rate of about two milliseconds per digit so that the entire display is updated every 16 milliseconds. In this preferred embodiment the counter 88 and the decoder 90 are part numbers SN7493 and SN74145, respectively, marketed by Texas Instruments and the drivers 84, 85 are part numbers DI-514, marketed by Dionics.
In addition, lines 1 through 4 of the control bus 92 are used to drive a switch matrix 100. A detailed view of the switch matrix 100 is shown in FIG. 5, in which lines 1 through 4 of the control bus 92 are indicated by reference number 122, 124, 126, 128, respectively. As previously mentioned, the decoder 90 operates to sequentially place an output signal on each of the lines of the control bus 92. Simultaneously, the microcomputer 80 is programmed to monitor lines on the eight-bit switch input bus 110 for signals. Seven of these lines are indicated by reference number 130-136 in FIG. 5. For example, when the decoder 90 places an output signal on line 122, the microcomputer registers a signal on line 130 as indicating closure of switch "F." Switch 137 is a schematic representation of the switches placed at each matrix mode which is in use.
FIG. 5 shows the 26 switch inputs. Here the symbols A, B, C, D, E and F at the extreme left hand edge of the matrix represent the reading station switches 54. The remaining nodes of the matrix correspond to the keyboard of the module 40. The arrangement of this keyboard is shown in detail in FIG. 6. As will be explained below, the keyboard switches 0-9, T and F are used by the user to enter proposed answers, the remaining keyboard switches are used by the user to control the operation of the microcomputer 80, and the display 120 is used by the microcomputer 80 to prompt the user and to display results.
The program of the microcomputer is listed in assembly language in Table 1. This listing provides a detailed description of the program. The following discussion presents a general description of the organization and operation of the program of Table 1.
When power is first applied or a new text key is supplied, the microcomputer first executes an initialization routine. In this initialization routine, the variable QN, which stores the current question number being processed, is set equal to 101. In addition, the program includes registers for each question, which registers are used to record the correctness of answers proposed by the user. During initialization, each of these registers is set to indicate incorrect responses.
In addition, certain parameters are calculated from the text key for later use by the program. The program of Table 1 utilizes a pseudo-random number generator (PRNG) to generate an answer key which designates the correct answer for each question in a series indicated by the text key. Pseudo-random number generators are well known to those skilled in the art. The Art of Computer Programming Semi-Numerical Algorithms, Vol. 2, by Donald Knuth, contains a discussion and several algorithms for pseudo-random number generators. In general, PRNG's are calculational routines which take an input number, called a seed, perform a calculation on the seed, and return a resulting value. The program of Table 1 is written to utilize a PRNG which accepts a six-bit seed and produces a six-bit resulting value. In addition, this PRNG produces a correct answer signal between 1 and 5; this signal is obtained by decoding the six-bit resulting value. For example, a resulting value between 1 and 13 can correspond to a correct answer signal of 1, a resulting value between 14 and 26 can correspond to a correct answer signal of 2, and so forth. By calling the PRNG repetitively, supplying the text signal as the seed for the first call and the resulting value from the previous call as the seed for the next call, a sequence of correct answer signals can be generated. The PRNG is chosen such that this sequence of correct answer signals is apparently substantially random, and a unique series of correct answer signals is generated for each seed used in the first call of the PRNG. Of course, a given text signal always results in the same sequence of correct answer signals, which corresponds to the correct answers for the questions of the textbook bearing that text signal.
During the initialization routine the PRNG is called repetitively, starting with the six-bit text key as a seed. The PRNG resulting values for each series (question 100, 200, . . . 900) are stored in RAM. As explained below, these values are used in determining the correct answer for any question between question number 101 and question number 999.
After the initialization a prompt message is displayed asking whether the user intends to work in the text mode or the study mode. The microcomputer repeatedly monitors the keyboard until either the TEST or the STUDY key is pressed by the user. Then a flag for either the test mode or the study mode is set, depending on which button was pressed. If the test mode has been selected the current value of QN is saved as an indication of the start of the test.
At this point the microcomputer 80 displays the question number currently being processed as well as a prompt message. The program then samples the keyboard and branches, depending on which key is registered by the microcomputer. Seven different branches are provided, as follows.
NEXT--If the NEXT key is registered, QN is incremented and QN is checked to see if the high order digit has changed, indicating a transition, such as from 199 to 200. If so, and the program is in the test mode, the score is automatically calculated and displayed as explained below, and the test or study prompt is again displayed. If in the study mode, the program merely returns to the test or study prompt. If the high order digit of QN is unchanged the program merely displays the incremented question number and waits for a new key.
SCORE--If the SCORE key is registered, the program calculates and displays the score, if in the test mode, or simply displays the last test score, if in the study mode. Then the program waits for another key. As explained below, the program records the accuracy of the proposed answer for each question while in the test mode. In order to display the score, the program simply indicates the number of correct answers and the number of total possible correct answers between the start of the test and the current question number. For example, one possible score is the message "7 of 9".
STUDY--If the STUDY key is registered while the program is in the study mode, the program continues to wait for another key. If the STUDY key is registered in the test mode, the program sets the study mode flag and then displays the question number and prompt message.
TEST--If the TEST key is registered while the program is in the test mode, the program continues to wait for another key. If the TEST key is registered in the study mode the program saves the current value of QN as the test start, sets the test mode flag, and then waits for another key.
GOTO--If the GOTO key is registered the program displays a prompt message and waits for additional keys. Keys 0-9 cause the program to save and display the key and to wait for additional keys. When three keys are registered, the program saves the three digit number as the new value of QN, and displays the new QN and a prompt message. The CLEAR key can be used to erase any partial entry of the new QN.
0-9, T, F--If one of these keys is registered, the program displays the entry and then waits for another key. The CLEAR key will cause the displayed entry to be blanked while the ANSWER key will cause the displayed entry to be registered as an answer signal indicative of a proposed answer.
The correct answer is then obtained by first getting the previously stored seed for the series of the current question. For example, if the current question number is 239, the appropriate previously stored seed is that for question 200. As previously explained, these previously stored seeds were generated by repeatedly executing the PRNG using the text key as the initial seed. Thus, the seed for question 200 (the 200 series) is obtained by executing the PRNG 200 times, starting with the text key as the initial seed. The previously stored seed for the current series is then supplied to the PRNG as a seed, and the PRNG is repetitively called the appropriate number of times to generate the answer key for the current question. In the above example involving question 239, the PRNG would be called 39 times, starting with the seed generated by the PRNG at the 200th execution of the PRNG. As previously explained, the PRNG generates a number between 1 and 5. If the current question is a 5 choice multiple choice question, the number generated by the PRNG indicates the correct answer. If the question is a true-false multiple choice question, two of the possible outputs of the PRNG (such as 1 and 2 for example) indicate that the correct answer is "True" and the remaining possible outputs (such as 3-5) indicate that the correct answer is "False".
The proposed answer is then compared with the correct answer as defined by the answer key to determine whether or not it is correct. If in the test mode, the appropriate register for the current question is then set to indicate whether the proposed answer was correct or not, and the program then waits for another key to be registered. If in the study mode, the program displays an appropriate feedback signal to indicate to the user whether the proposed answer is correct or not. If the proposed answer is correct, the program waits for another key to be registered. If the proposed answer is incorrect, the program waits for a CLEAR key or a NEXT key. If the CLEAR key is registered, the program clears the display, and then waits for another key to be registered. If the NEXT key is registered, the program increments QN as described above.
REVIEW--If the REVIEW key is registered while in the test mode, the program automatically calculates and displays the score as explained above and sets the study mode flag. If the REVIEW key is registered a second time the program displays the question number of the first missed question in the test along with a prompt message and then waits for a proposed answer. After a proposed answer is entered, the program immediately evaluates the correctness of the proposed answer and supplies the user with an appropriate feedback message. The program will accept multiple proposed answers, giving appropriate feedback in each case. The user can advance to the next missed question by depressing the REVIEW key again.
The program also includes a monitoring routine that reads the text signal from the switches 54 periodically, each time the switch matrix is read. The text signal is automatically compared with the text signal previously in use. If the two are not identical, the program automatically resets and reinitializes in order to prevent an inaccurate answer key from being used. The text signal corresponding to no perforations is not a legitimate text signal, but is instead taken to indicate the absence of a text book in the reading station.
Having described the structure and programming of this preferred embodiment, its operation can now be discussed. To begin, the cover 48 of the reading station 46 is opened and the flap 24 is positioned with the registration holes 26 over the registration pins 50. Then the cover 48 is closed to cause the flap 24 to impose the text key on the digital switches 54. The ON key is pressed to supply power to the module 40, and the display comes up with the prompt message "S or T?" Depending on whether the TEST or STUDY key is pressed, the module enters either the test or study modes.
If the TEST key is pressed the module responds with the prompt message "101?" The user can now propose an answer to question 101 (printed in the text book) with the keyboard. The proposed answer will be displayed along with the question number. Once the user is satisfied with his proposed answer, he pushes the ANSWER key and the proposed answer is tabulated. By pressing the NEXT key the user can now advance to the next question and enter another proposed answer. This process is repeated until the end of the test is reached. Pressing SCORE will cause the score to be calculated and displayed. After the test, the user can review his mistakes by pressing the REVIEW key. This causes the module to display the question number of the first missed question of the test. At this point the user can select and enter another proposed answer, and the display will indicate whether or not the new proposed answer is correct. The user can enter any number of proposed answers, and then advance to the next missed question by pressing the REVIEW key. Pressing the OFF key turns off the module.
If the study mode has been selected, the prompting and entry of proposed answers is as described above. However, after each answer is entered with the ANSWER key, the display immediately indicates whether the proposed answer is correct or not and the user can try multiple proposed answers on any one question. As before, the NEXT key is used to advance to the next question. In addition, the GOTO key can be used to go to any desired question number, and the CLEAR key can be used to clear the display.
From the foregoing, it should be apparent that this preferred embodiment is capable of automatically sensing a text key associated with a text book to allow the teaching device to simply and readily generate the appropriate answer key. The device utilizes a novel and advantageous method to generate the answer key from the text key with small memory requirements and yet great flexibility.
Of course, it should be understood that various changes and modifications to the preferred embodiment described herein will be apparent to those skilled in the art. For example, in alternate embodiments the program can be modified to accept a text key which is manually keyed in via the keyboard by the user in response to instructions contained in the text book. Alternately, other sensing means, such as optical or magnetic sensors, can be used in the means for automatically sensing the text key. In addition, the electronics can be miniaturized to a custom single chip which dispenses with most of the discrete logic chips shown in FIG. 4 and is battery powered. It is therefore intended that all such changes and modifications be covered by the following claims.
Claims
I claim:
1. A teaching device comprising: means for automatically sensing an encoded text key and generating in response thereto a digital seed; means, responsive to the seed, for automatically performing an arithmetic calculation on the seed to generate a unique set of digital answer key signals indicative of a sequence of correct answers, at least some of said correct answers corresponding to respective questions associated with said text key; means for registering a manually generated answer signal indicative of a proposed answer to a selected one of said questions; and means for automatically comparing the manually generated answer signal with the set of answer key signals to determine whether the proposed answer corresponds to the respective correct answer.
2. The invention of claim 1 wherein the sensing means includes a plurality of digital switches positioned to read a digital text key encoded on a surface of a text book.
3. The invention of claim 2 wherein the plurality of digital switches are mechanical switches activated by a text key which includes a physical digital pattern encoded on the surface of the text book.
4. The invention of claim 2 or 3 wherein the plurality of digital switches are positioned to read a text key encoded as a strip on a marginal edge of the surface of the text book.
5. The invention of claim 2 or 3 wherein the plurality of switches are adapted to sense the presence or absence of a punched hole formed in the surface of the text book.
6. The invention of claim 1 wherein the means for performing an arithmetic calculation comprises a pseudo-random number generator and means for supplying the seed as an input signal to the pseudo-random number generator to generate the set of answer key signals.
7. A teaching device comprising in combination: a text book; a text key encoded on a surface of the text book; means for automatically sensing an encoded text key and generating in response thereto a digital text signal indicative of a text key number; means, responsive to the text signal, for automatically performing an arithmetic calculation on the text signal to generate a unique set of digital answer key signals indicative of a sequence of correct answers, at least some of said correct answers corresponding to respective questions associated with said text key; means for registering a manually generated answer signal indicative of a proposed answer to a selected one of said questions; and means for automatically comparing the manually generated answer signal with the set of answer key signals to determine whether the proposed answer corresponds to the respective correct answer.
8. The invention of claim 7 wherein the text key is digitally encoded and the sensing means includes a plurality of digital switches positioned to read the text key.
9. The invention of claim 8 wherein the text key includes a physical digital pattern encoded on the surface of the text book and the plurality of digital switches are mechanical switches.
10. The invention of claim 8 or 9 wherein the text key is encoded as a strip on a marginal edge of the surface of the text book.
11. The invention of claim 8 or 9 wherein each of the plurality of switches is adapted to sense the presence of absence of a punched hole formed in the surface of the text book.
12. The invention of claim 7 wherein the means for performing an arithmetic calculation comprises a pseudo-random number generator and means for supplying said text signal to the pseudo-random number generator as a seed to generate the set of answer key signals.
13. A teaching device comprising: a housing; a plurality of digital switches mounted on the housing and arranged to sense a text key on a text book positioned adjacent the switches and to generate in response thereto a digital seed; means, responsive to the seed, for automatically performing an arithmetic calculation on the seed to generate a set of digital answer key signals indicative of a sequence of correct answers, at least some of said correct answers corresponding to respective questions associated with said text key; means for registering a manually generated answer signal indicative of a proposed answer to a selected one of said questions; and means for automatically comparing the manually generated answer signal with the set of answer key signals to determine whether the proposed answer corresponds to the respective correct answer.
14. A teaching device comprising: a housing; a text book positioned adjaent the housing; a text key digitally encoded on a surface of the text book; a plurality of digital switches mounted on the housing and arranged to sense the text key and to generate in response thereto a digital seed; means, responsive to the seed, for automatically generating a set of digital answer key signals by performing a digital calculation on the seed to generate the answer key signals, said answer key signals indicative of a sequence of correct answers, at least some of said correct answers corresponding to respective questions associated with said text key; means for registering a manually generated answer signal indicative of a proposed answer to a selected one of said questions; and means for automatically comparing the manually generated answer signal with a respective one of the answer key signals to determine whether the proposed answer corresponds to the respective correct answer.
15. The invention of claim 13 or 14 wherein the plurality of digital switches are mechanical switches activated by the text key, and the text key includes a physical digital pattern encoded on the surface of the text book.
16. The invention of claim 13 or 14 wherein the plurality of digital switches are positioned to read the text key, and the text key is encoded as a strip on a marginal edge of the surface of the text book.
17. The invention of claim 13 or 14 wherein each of the plurality of switches is adapted to sense the presence or absence of a punched hole formed in the surface of the text book.
18. The invention of claim 13 or 14 wherein the means for generating a set of digital answer key signals includes a pseudo-random number generator and means for supplying the seed to the pseudo-random number generator as an input signal to generate the answer key signals.
19. The invention of claim 1 or 13 or 14 wherein the means for performing a calculation comprises: a pseudo-random number generator, responsive to a digital input signal, for generating a pseudo-random output number; means for supplying the seed to the pseudo-random number generator as the input signal to generate a first output number representative of a first correct answer included in the sequence of correct answers; means for supplying the first output number to the pseudo-random number generator as the input signal to generate a second output number representative of a second correct answer included in the sequence of correct answers; and means for supplying the second output number to the pseudo-random number generator as the input signal to generate a third output number representative of a third correct answer included in the sequence of correct answers.
20. The invention of claim 1 or 13 or 14 wherein the means for performing a calculation comprises: a pseudo-random number generator, responsive to an input signal, for generating a pseudo-random output number; means for supplying the seed to the pseudo-random number generator as the input signal; means for repeatedly supplying the output number to the pseudo-random number generator as the input signal to generate a sequence of output numbers, at least a plurality of which are representative of corresponding correct answers included in the sequence of correct answers.
21. A teaching device comprising: means for registering a text key and generating in response thereto a digital text signal indicative of a text key number; means for automatically performing a calculation based on said text signal to generate a set of digital answer key signals, said answer key signals indicative of a sequence of correct answers, at least some of said correct answers corresponding to respective multiple choice questions associated with said text key; means for registering a manually generated answer signal indicative of a proposed answer to a selected one of said questions; and means for automatically comparing the manually generated answer signal with a respective one of the answer key signals to determine whether the proposed answer corresponds to the respective correct answer.
22. The invention of claim 21 wherein the means for performing a calculation includes a pseudo-random number generator and means for supplying said text signal to the pseudo-random number generator as a seed to generate the set of answer key signals.
23. A teaching device comprising: means for registering a text key and generating in response thereto a digital seed; a pseudo-random number generator, responsive to a digital input signal, for generating a pseudo-random output number as a result of an arithmetical calculation on the input signal; means for supplying the seed to the pseudo-random number generator as the input signal to generate a unique set of digital answer key signals, said answer key signals indicative of a sequence of correct answers, at least some of said correct answers corresponding to repective multiple choice questions associated with the text key; means for registering a manually generated answer signal indicative of a proposed answer to a selected one of said questions; and means for automatically comparing the manually generated answer signal with a respective one of the answer key signals to determine whether the proposed answer corresponds to the respective correct answer.
24. A teaching device comprising in combination: a text book, said text book including a plurality of page, said pages bearing a plurality of questions and a plurality of sets of possible multiple choice answers, each set of answers corresponding to a respective one of said plurality of questions; a text key encoded as a pattern of perforated and unperforated regions positioned along a marginal portion of one of the pages; a housing; means for releasably holding the marginal portion in registration with the housing such that the text key is maintained in position adjacent the housing; a plurality of mechanical switches mounted in the housing and positioned such that each of the switches is adjacent one of the perforated and unperforated regions and the switches sense the pattern of perforated and unperforated regions and generate in response thereto a binary text signal indicative of a text key number; a computer, responsive to the text signal; means, included in the computer, for generating a pseudo-random number as a function of a seed input signal; means, included in the computer, for supplying the text signal to the generating means as the seed input signal to obtain a unique set of digital answer key signals, said answer key signals indicative of a sequence of correct answers, at least some of said correct answers corresponding to respective ones of said plurality of questions; means, included in the computer, for registering a manually generated answer signal indicative of a proposed answer to a selected one of said plurality of questions; and means, included in the computer, for automatically comparing the manually generated answer signal with a respective one of the answer key signals to determine whether the proposed answer corresponds to the respective correct answer.