Abstract:
Jigsaw puzzles for use by young children to practice elementary arithmetic. Each puzzle is circular and includes a center piece, four middle ring question pieces, and twelve outer ring answer pieces. One side of each puzzle contains the arithmetic question and answer pieces and the other side forms a picture when the question and answer pieces are put together correctly. A transparent tray is used for assembling the pieces of the puzzle. A transparent cover is adapted to be snapped into place over the tray and allow the container to be turned over to view the picture side to determine if the picture is either (1) correct, which means that all of the arithmetic questions have been answered correctly or (2) incorrect, which means that some or all of the arithmetic questions have not been answered correctly.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to jigsaw puzzles for use by young children as an aid to learning elementary arithmetic, i.e., addition, substraction, multiplication and division. 
     A number of puzzle devices for teaching elementary mathematics to young children have been proposed. 
     U.S. Pat. No. 4,360,347 describes a mathematical educational game device. The embodiment illustrated in FIGS. 1-3 is in the form of a circular puzzle having a plurality of pieces  15 . The puzzle has no center piece (being open in the middle) and a plurality of wedge-shaped puzzle members  15 . Numbers or arithmetic operators are printed on one side of the puzzle members  15 . Each radial column is comprised of four pieces, the outer row containing a number, the next inner row containing an arithmetic operator, the next inner row containing the question number and the inner row containing the answer number. Problems can also be similarly presented and solved within each circumferential row. 
     U.S. Pat. No. 2,875,531 describes an educational device of interlocked puzzle pieces  15 . A frame  10  is comprised of frame members  11  enclosing a front transparent window  12  set in slots  13 . A rear cover  16  is inserted into slots  17 . The puzzle pieces  15  are put together following the instructions contained on the rear cover  16  of frame  10 , reading down the left column first and then moving down the right column. The puzzle pieces  15  are put together moving always in a clockwise direction, forming the border first. Where, for example, the instructions call for “1+1”, the student places the puzzle piece  15  containing the number “2”. When the puzzle pieces are put together properly, a picture  14  is formed on the side of the puzzle opposite to the answer side of pieces  15 . It does not appear that the pieces  15  could be interlocked together other than in the correct way. The picture  14  is not used to check the answers selected; it is merely the product of putting the puzzle together as in any jigsaw puzzle. 
     U.S. Pat. No. 4,422,642 describes an educational puzzle for various skills, including mathematics. The puzzle, when assembled, is rectangular in shape. In the embodiments illustrated in FIGS. 1 and 2, there are three rows and three columns of interlocking puzzle pieces containing arithmetic questions and answers in both the horizontal rows and vertical columns. In the embodiment of FIG. 2, the three columns are color coded. The pieces can be interlocked in only one way, i.e., they cannot be assembled to proved wrong answers. 
     U.S. Pat. No. 5,743,741 describes a math jigsaw puzzle. The puzzle, when assembled, is rectangular in shape. Although several embodiments are described, they all operate on the same principal as that shown in FIGS. 1A-1L in which one starts with a center piece 24 which has a central number in large print surrounded by four equally spaced numbers in smaller print (see FIG. 1-F). One then interlocks a piece 30 to the center piece 24 to solve the problem presented by the central number and adjacent surrounding number of the center piece, as shown in FIG. 1-G. Each added piece 30 presents a new math problem which is solved by interlocking a further solution piece, as shown in FIGS. 1-H through 1-L. The pieces can be interlocked in only one way, i.e., they cannot be assembled to provide wrong answers. 
     A problem with all of these prior art puzzles is that none of the them can have their pieces interlocked together to provide a wrong answer and a way to clue the child that his/her answer is wrong, thereby causing the child to re-think and re-work his wrong answer. It is an object of the present invention to provide such a math teaching puzzle. 
     SUMMARY OF THE INVENTION 
     The present invention relates to four sets of jigsaw puzzles designed to assist young children in learning elementary arithmetic. One of the four sets is designed to aid in learning elementary addition, one set for elementary subtraction, one set for elementary multiplication, and one set for elementary division. Each set is comprised of a plurality of puzzles of varying complexity. Preferably a set is comprised of ten puzzles which provides a separate puzzle for arithmetic questions involving operating numbers selected from 1 through 10. 
     Each puzzle is circular and essentially two dimensional. Each puzzle is comprised of a center piece, four middle ring question pieces, and twelve outer ring answer pieces. 
     One side of each puzzle contains the arithmetic question and answer pieces and the other side forms a picture when the question and answer pieces are put together correctly. The printed pattern forming the background to the question side of the puzzle is preferably different for each puzzle so pieces cannot be inadvertently mixed up. 
     Each puzzle comes in a container that includes a transparent tray and transparent cover. The transparent tray is for assembling the pieces of the puzzle. The transparent cover is adapted to be snapped into place over the tray and allow the container to be turned over to view the picture side and determine if the picture is either (1) assembled properly (which means that all of the arithmetic questions have been answered correctly) or (2) assembled improperly (which means that some or all of the arithmetic questions have not been answered correctly). 
     The circular center piece contains twelve evenly spaced apart and different numbers (“operands”) located adjacent its periphery. The center piece has a peripheral keying projection adjacent one of the operand numbers. The four middle ring question pieces have concave inner sides that constitute a chord having a length that is one fourth the circumference of the circular center piece. The concave inner sides are adapted to matingly fit against the outer periphery of the center piece, with the concave inner side of one of the four pieces (the “keystone piece”) having a keying recess adapted to receive the keying projection extending from the center piece. The sides of the four middle ring question pieces have convexities (tabs) and concavities (recesses) of varying shapes with the tabs of one piece being adapted to be interlocked to a mating recess of an adjacent piece. Thus, the keystone piece fits at only one location adjacent the center piece (with the center piece keying projection being received into the mating keying recess of the keystone piece) while the user needs to place the other three question pieces in specific locations so that the sides of adjacent pieces interlock. 
     Each of the question pieces have arithmetic questions located radially adjacent each of the operand numbers located on the center piece. The arithmetic questions include an operator sign (+, −, ×, or ÷) followed by an operator number (preferably selected from 1 through 10) and an equal (=) sign. For each puzzle the arithmetic questions are all identical. For example, all of the arithmetic questions appearing on the question pieces of one puzzle in the addition set will contain the math question “+1=”, which questions are located radially adjacent the operand numbers on the center piece. 
     The outer edge (periphery) of each of the four question pieces contain three identical convex tabs extending therefrom, each tab being an identical arc of a circle. 
     The twelve outer ring answer pieces are identical in shape, with a concave inner edge (recess) adapted to interfit with each and every one of the convex tabs of the question pieces. Thus, the user must interfit the concave recess of the answer piece to the convex tab of the question piece that the user believes supplies the correct answer. For example, if the center piece had the operand number “11” followed by the arithmetic question “+1” radially adjacent on the question piece, the correct answer piece would be the one having the number “12” located thereon. However, since the outer ring answer pieces are all identical in shape, it is possible to interfit an outer ring answer piece containing the wrong answer to the arithmetic question located on the question piece. 
     After the child has interfit all of the puzzle pieces together, he/she can snap the transparent container cover onto the transparent container tray and turn the puzzle container over to see if the picture on the other side is correct. If correct, it means that the user has selected all of the correct answers to the questions. If the picture is not correct, it means that the user has selected two or more wrong answers. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top plan view of the arithmetic jigsaw puzzle of the present invention with the interfitted pieces left blank to show the shapes of the center piece, middle ring question pieces and outer ring answer pieces; 
     FIG. 2 is a top plan view of the arithmetic jigsaw puzzle of the present invention, illustrating an addition puzzle; 
     FIG. 3 is a top plan view of the arithmetic jigsaw puzzle of the present invention, illustrating a substraction puzzle; 
     FIG. 4 is a top plan view of the arithmetic jigsaw puzzle of the present invention, illustrating a multiplication puzzle; 
     FIG. 5 is a top plan view of the arithmetic jigsaw puzzle of the present invention, illustrating a division puzzle; 
     FIG. 6 is a bottom plan view of the arithmetic jigsaw puzzle of the present invention, illustrating a picture contained on that side of the puzzle opposite the side of the jigsaw puzzle having the arithmetic questions and answers thereon; 
     FIG. 7 is plan view of the inside of the container tray used to hold the puzzle pieces as they are interfitted together; and 
     FIG. 8 is a plan view of the inside of the container cover which snaps onto the container tray to form a puzzle container which can be turned over to examine the picture on the side of the puzzle opposite to that side having the arithmetic questions and answers. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     As mentioned previously, the present invention is comprised of four sets of jigsaw puzzles, one of the four sets being designed to assist in learning elementary addition, one set for elementary substraction, one set for elementary multiplication, and one set for elementary division. Each set is comprised of a plurality of puzzles, preferably ten. 
     FIG. 1 is a top plan view of puzzle  10  showing the various pieces interfitted without the presence of any arithmetic problems. 
     Puzzle  10  with all of its pieces interfitted is circular and comprised of a center piece  20 , four middle ring question pieces  30 A- 30 D, and twelve outer ring answer pieces  40 A- 40 L. 
     The center piece  20  is circular shaped with a generally triangular shaped indexing finger  22  projecting from the periphery thereof. 
     The four middle ring question pieces  30 A- 30 D have concave inner sides  32 A- 32 D, respectively that constitute a chord having a length that is one fourth the circumference of the circular center piece  20 . The concave inner sides  32 A- 32 D are adapted to matingly fit against the outer periphery of the center piece  20 . The concave inner side of middle ring question piece  30 A (the “keystone piece”) has an indexing recess  33  adapted to receive the indexing finger  22  extending from the center piece  20 . 
     The first sides  34 A- 34 D and the second sides  34 ′A- 34 ′D of the four middle ring question pieces  30 A- 30 D, respectively, have convexities (tabs) and concavities (recesses) of varying shapes with the tabs of one question piece  30  being adapted to be interfit with a mating recess of an adjacent question piece  30 . 
     The keystone question piece  30 A fits at only one location adjacent the center piece  20  with the center piece  20  indexing projection  22  being received into the mating indexing recess  33  of the keystone piece  30 A. The user needs to place the other three question pieces  30 B- 30 D in specific locations so that the sides of adjacent pieces interfit. Although all of the question pieces of a particular puzzle  10  carry identical arithmetic questions, the purpose of requiring the question pieces  30  to have different shapes and able to be placed only in specific locations about center piece  20  is so that the picture appearing on the bottom face of puzzle  10  will be correct insofar as the center piece  20  and question pieces  30  are concerned. 
     The outer edges (periphery)  36 A- 36 D of each of the four question pieces  30 A- 30 D, respectively, contain three identical convexities (tabs) extending therefrom, each tab being an identical arc of a circle. 
     The twelve outer ring answer pieces  40 A- 40 L are identical in shape, each having a concave inner edge (recess)  42 A- 42 L, respectively, adapted to interfit with any of the convex tabs of the question pieces  30 A- 30 D. 
     First sides  44 A- 44 L and second sides  44 ′A- 44 ′L of answer pieces  40 A- 40 L, respectively, are angled as shown, and if extended inwardly would all meet at the center of circular center piece  20 . 
     The outer edges  46 A- 46 L of answer pieces  40 A- 40 L, respectively, are all identical and are an arc of the circle formed by puzzle  10 , the length of each arc being {fraction (1/12)}th the circumference of the circular puzzle  10 . 
     The center piece  20  has twelve evenly spaced apart operand numbers printed thereon. The operand numbers are the numbers that are to be operated upon by arithmetic questions located in radial alignment therewith on the question pieces  30 A- 30 D. In multiplication the operand number would be called the “multiplicand”; in division the operand number would be called the “dividend”. 
     Each of the four question pieces  30 A- 30 D is situated opposite three adjacent operand numbers located on the center piece  20 . Therefore, each of the four question pieces  30 A- 30 D have three arithmetic questions printed thereon, each in radial alignment with an operand number located on center piece  20 . 
     Each of the arithmetic questions contains three elements. 
     The first element in the arithmetic question is the arithmetic operator sign, i.e., either an addition sign (+), subtraction sign (−), multiplication sign (×) or division sign (÷). For a given puzzle, the arithmetic operator sign is the same for all twelve arithmetic questions, i.e., the puzzle is either an addition puzzle, subtraction puzzle, multiplication puzzle or division puzzle. 
     The second element in the arithmetic question is an “operator” number that is to be added to, subtracted from, multiplied times or divided into the operand number. In multiplication this operator number would be called the “multiplier”; in division this operator number wold be called the “divisor”. For each puzzle, all of the operator numbers are identical. 
     The third element in the arithmetic question is always an equal sign (=) 
     Each of the twelve outer ring answer pieces  40 A- 40 L contain only a single number, an “answer” number. Since outer ring answer pieces  40   a - 40 L all have identical shapes and each can be abutted in radial alignment with any of the twelve arithmetic questions printed on the four question pieces  30 A- 30 D, wrong answers can be selected for two or more of the arithmetic questions. 
     FIGS. 2-5 show examples of an addition puzzle  110 , subtraction puzzle  210 , multiplication puzzle  310 , and division puzzle  410 , respectively. 
     FIG. 7 shows a transparent tray  50  into which are placed the various puzzle pieces. Tray  50  is generally rectangular in shape, but has one corner that is rounded. Tray  50  includes a tray floor  51  and a circular inner wall  52  extending upwardly from tray floor  51 . The circular inner wall  52  has a radius “R” equal to the radius of puzzle  10 . An outer wall  53  has a flange  54  extending outwardly from the bottom thereof. Shelves  55  are formed between the top of outer wall  53  and the top of inner wall  52 . Twelve finger recesses  56  are formed in inner wall  52  and floor  51 . Large lock tabs  57  are formed in outer wall  53 . A plurality of small lock recesses  58  are formed in outer wall  53 . Tray unlocking tab  59  extends outwardly from that portion of flange  54  located in the rounded corner of tray  50 . 
     Center piece  20  would be placed at the center of the floor  51  of tray  50 , keystone piece  30 A having the indexing recess  33  would be placed so that indexing finger  22  is inserted into indexing recess  33 , and the remaining three question pieces  30 B- 30 D would be placed where their respective sides can be properly interfitted into place. Finally, answer piece  40  deemed to contain the correct answer for each arithmetic question would be selected from amongst the answer pieces  40 A- 40 L and fitted into radial alignment with that arithmetic question. 
     Transparent cover piece  60 , shown in FIG. 8, is generally rectangular in shape but has one corner thereof that is rounded. Cover piece  60  includes an inner top surface  61 , side wall  62  extending upwardly from inner top surface  61 , and flange  64  extending outwardly from side wall  62 . Large lock recesses  67  are formed in side wall  62 , as shown. Small lock tabs  68  extending inwardly from side wall  62 . A cover unlocking tab  69  extends outwardly from that portion of flange  64  located in the rounded corner of cover piece  60 . 
     To check the accuracy of the answers, transparent cover piece  60  would be snapped into place over transparent tray  50  to hold the puzzle pieces in place, and the container formed by tray  50  and top  60  turned over to inspect the picture appearing on the reverse side of the puzzle, such as, for example, the picture shown in FIG. 6 . If the picture is correctly shown it means that all of the arithmetic questions have been answered correctly. If the picture is not correctly shown it means that two or more of the arithmetic questions has been answered incorrectly, and the puzzle can be reviewed and answer pieces  40  moved to correct erroneous answers. 
     By “picture” it is intended to include any visual representation that would be perceived as being correct if all of the answer pieces  40  have been properly placed radially adjacent the arithmetic questions, and would be perceived as incorrect if two or more of the answer pieces  40  have been improperly placed radially adjacent the arithmetic questions. Such visual representations include, but are not limited to, any two dimensional work of fine, graphic or applied art, photographs, prints, art reproductions, maps, charts, technical drawings, diagrams, etc. 
     It is preferable to print a unique background pattern to each of the puzzles  10  so that pieces from one puzzle aren&#39;t inadvertently mixed in with pieces from another puzzle. Such patterns can be in color or black and white, and are a matter of infinite choice. Examples of such patterns have not been shown in the drawings for sake of clarity. 
     It will be obvious to those having skill in the art that many changes may be made to the details of the above-described embodiments of this invention without departing from the underlying principles thereof. The scope of the present invention should, therefore, be determined only by the following claims.