Didactic-educational toy for elementary arithmetic operations, reading and writing

A didactic-educational toy for elementary arithmetic operations includes a plurality of transparent plates. Each of the transparent plates has ten circular orifices. The orifices are distributed symmetrically in two rows. Each row has five of the orifices. Each of the orifices has substantially the same diameter. A plurality of plates each has cylindrical stepped protuberances. Each of the protuberances has a base with a diameter corresponding to a diameter of the orifices of the transparent plates to provide for close-fitting insertion of the base into a corresponding one of the orifices. Each of the protuberances has an upper portion having a diameter smaller than the diameter of its base to facilitate the insertion of the protuberance into a corresponding orifice. The plurality of plates, which have cylindrical stepped protuberances include plates has a different number of protuberances. The surface area of each plate is substantially proportional to the number of protuberances. The plurality of plates, which have cylindrical stepped protuberances include at least a plurality of plates having only one protuberance and a plurality of plates having two protuberances.

This application is a continuation of PCT/RS94/00030, filed Mar. 22, 1994. 
FIELD OF THE INVENTION 
As is expressed in the title of this specification, the present invention 
refers to a didactic-educational toy for elementary arithmetic operations, 
reading and writing, which provides a series of relevant and advantageous 
features with regard to the presently existing devices for these 
activities. The child's imagination is also exercised due to the fact that 
the pieces can be connected as a construction, obtaining three-dimensional 
geometric shapes as there are varied connection and joining pieces. 
The different elements that identify the digits have some corresponding 
protuberances that make the represented number identifiable by touch. 
Upon handling the different elements that comprise the toy, mental 
calculation and the interest to learn how to read and write are enhanced 
to a larger degree than with other means and devices presently on the 
market. 
Upon carrying out operations and forming the tens, the same are more easily 
identifiable. There are also figurative pieces that allow one to study the 
spatial concepts of left, right, up, etc., stimulating the child's oral 
expression as problematic situations arise, making the didactic toy more 
attractive. 
All the components parts are easily interconnected, which allows the base 
surface to be increased in order to carry out operations, as well as to 
form words and sentences. 
BACKGROUND OF THE INVENTION 
There are presently means or tools to carry out this type of operations, 
consisting of prismatic slide rules of different lengths and colors, 
abacuses and other types of boxes containing cubes, slide rules and 
boards. 
With these elements, upon being very repetitive, carrying out elementary 
operations becomes tremendously difficult, and on the other hand the basic 
digits are not identifiable by touch. Figurative pieces that can be 
assembled to study the spatial concepts of left, right, etc. and to 
stimulate oral expression, as well as graphic expression, mathematical as 
well as to start the learning of reading and writing, are not known 
either. 
In general lines, in order to achieve the above cited advantageous 
characteristics, as well as to eliminate the inconveniences cited in the 
prior art, the didactic-educational toy for elementary arithmetic 
operations, reading and writing, that constitutes the object of the 
invention, is comprised of a series of parts or elements that we can 
distribute in two big groups: one of them that comprises all the parts 
that allow elementary aritmetic operations to be done, and the other that 
includes another part and letter cards to form words and sentences. 
The following elements belong to this first group: 
a) Ten rectangular plates from whose top surface ten dowels distributed in 
two rows of five emerge, these being the base pieces upon which other 
plates representative of digits will be inserted, as we will see 
hereinafter. In the base of each dowel there is a fine cylindrical 
widening to facilitate the lifting of the first inserted plate. 
These plates with dowels have a peripheral furrow or groove, made in the 
edges, thus the coplanar connection of these plates can be carried out, 
with the help of some boards of lengths corresponding to the sides, 
inserted in said grooves. 
Each rectangular plate is green on the top surface and white on the bottom 
surface, representing the tenth part of a hundred's place that would be 
formed upon assembly ten plates, identifying the hundred's place. As we 
will see later on, the color red will be used to mark the ten's place, and 
blue to define the one's place. 
b) Elongate boards, colored red that, as we have indicated above, serve to 
join two green rectangular plates, remaining perfectly assembled and the 
red color thereof meaning the fact that a ten has already been surpassed, 
as we will see later on. Besides, these boards can replace other elements 
that mark the ten's place, carrying out an abstraction and simplification 
process. Therefore, one of the elongate boards can be placed 
longitudinally between the dowels of the plates, visualizing ten of them 
when the ten plates are assembled with dowels. 
c) A series of thinner plates representative of digits (from 1 to 10). The 
surface of the plate corresponding to number 10 coincides with the plate 
with dowels, the one of number 1 being the tenth part of the total 
surface. The surface of number 2 is equivalent to two-tenth parts, and so 
on, forming the different numbers from two parallel pair alignments, 
representative of the preceding even number. 
Each one of these thin plates has some stepped cylindrical protuberances, 
provided with a through hole located in the center point thereof and whose 
diameter is equivalent to that of the dowels of the base plates to 
facilitate the stacking thereof upon breaking sown a number. There is a 
blue colored perimetric strip, with the exception of the plate that 
defines number 10 which is red as it corresponds to a ten. 
Besides they have some hollow spaces with specific shapes in their contour 
in order to make the identification of the number of cylindrical 
protuberances easier, or the counting thereof by groups. 
In order to facilitate the lifting or release of the plates with dowels due 
to their slight thickness, it has been provided for that they can include 
some points thickened on the bottom surface thereof, in replacement of the 
cylindrical widenings of the base of the dowels. 
When these thinner plates, representative of digits, are inserted in the 
rectangular plates with dowels, the ends of the latter project in order to 
allow the identification thereof by touch. 
d) Transparent templates, of an identical surface as that which corresponds 
to the number 10, with a red perimetric strip on the edge and ten circular 
orifices that allow tight insertion in the cylindrical protuberances of 
the digital plates, the latter already inserted in the plates with dowels, 
thus the tens that are being formed upon operating can be visualized. 
e) A rectangular mold with housings in which the digital plates themselves 
fit, with identification of the shape by the student, there being some 
lateral recesses to facilitate the lifting of the inserted plates. In the 
top part of each housing there is a circle drawn containing the furrow of 
the shape and the mnemonic drawing thereof that thus helps one to remember 
the figure. In this way one manages to identify the number with its shape 
and to write it, operating as a digital plate. This furrow defines a path 
to be followed by a pencil or scriber, starting from an initial point 
preferably distinguished in red, thus the automatization and correct 
tracing of the shape are facilitated. 
f) There is also a series of figurative parts that, assembled in the edges 
of the rectangular plates with dowels, allow the study of spatial concepts 
of left, right, up, etc. stimulating oral expression as problematic 
situations arise and making the toy more attractive. 
g) Assembly parts of the different digital plates that are incorporated in 
the stepped stubs. They are "X" shaped or double "X"-shaped with small 
inside protuberances in the ends of their arched branches, these 
protuberances inserting in respective recesses existing diametrically 
opposite in the widest part of the stepped cylindrical protuberances. 
h) Pincers for fastening the figurative plates and other elements that we 
will see hereinafter, related to the second group of cards and elements 
for reading and writing. One of the limbs of these fastening pincers, has 
a cylindrical stub that can be inserted in one of the cylindrical recesses 
of the bottom face of the digital plates, these pincers being rigid or 
articulated in order to change the plane. 
i) Small rectangular plates with two orifices or two pairs of them and the 
mathematical sign "plus" drawn thereon, in which the portions with the 
largest diameter of the stepped cylindrical protuberances of the digital 
plates are inserted, allowing one to add them up and these little plates 
act as assembly elements and they are to be used in the event that the 
small children who play with the toy cannot use the "x"-shaped assembly 
parts due to the risk involved in their small size. 
j) Articulating parts that include an articulating head that allows 
movement like a hinge, turning 90.degree. on both sides in order to change 
the plane and to form different angular positions with the different 
component parts of the toy. The maximum rotation limit positions, as well 
as the coplanar one and the other intermediate positions are stable. These 
articulating parts have in one of the faces irrespective of the geometric 
shape thereof, one or several annular bulges that are susceptible to 
fitting in the corresponding annular channel of the bottom face of the 
digital plates, provided for this purpose. It also has some flexible end 
tongue pieces that facilitate disassembly. These articulating heads can 
also be inserted in the tongue pieces that are inserted in the perimetric 
groove of the plates with dowels or in the one also existing in other 
digital plates that have a thickness equivalent to that of the plates with 
dowels. 
k) Plates with stepped cylindrical protuberances and a thickness equivalent 
to that of the plates with dowels representing the different digits and 
just like the latter they include the perimetric groove on the edge, also 
including some recesses or slits that define a castellated contour, 
joining together the different plates with grooved and tongued coupling 
tongue pieces. 
l) Decorative pieces that have protuberances to fit in the castellated 
recessed of the plate, aside from partially inserting in the perimetric 
groove. One of these decorative pieces has a triangular or rectangular 
shape and represents half the unit which is also usable in architure upon 
building houses, dolls, etc. 
As we had indicated before, the didactic educational toy included other 
parts or elements that make up what we have called the second group of 
cards, apt for learning how to read and write. They are basically the 
following: 
a) Cards apt for learning how to read and write, having a different contour 
and color for the consonants and for vowels. The consonants may be printed 
on rectangular cards and the vowels or circular cards, for example. 
b) Molds or plates provided with housing to place the vowels and consonants 
individually. Hence, marking the rectangular or circular contour of the 
letters is made possible in order to later trace or delineate the shape 
thereof. 
c) Cards with allegorical drawings of the words that are printed on one of 
the surfaces thereof, while on the reverse side of the same there is only 
the rectangular or circular mark of consonants and vowels, respectively, 
therefore not including the written word. This may be used so that two 
contestants, discovering words or sentences previously positioned on a 
board, play. 
One or more plates with stepped cylindrical protuberances and that have a 
castellated contour can be used as a board. In each one of the slots a 
card fit in just like the decorative figures can be placed, these cards 
having a tongue piece and a groove in opposite positions, for the grooved 
and tongued coupling thereof and to thus permit the forming of words that 
can be separated by other blank cards or that contain a period. 
The cards that include the allegorical drawings of the words appearing on 
them, are fastened to the plates by means of pincers, one of whose limbs 
is inserted in the perimetric groove, which may be provided with small 
reliefs to optimize anchoring. 
To provide a better understanding of the features of the invention and 
forming an integral part of this specification, some sheets of drawings in 
whose figures the following has been represented in an illustrative and 
non-restrictive manner, are attached hereto.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Making reference to the numbering used in the figures we can see how the 
didactic-educational toy for elementary arithmetic operations, reading and 
writing, that the invention proposes, includes a series of elements or 
parts that can be assembled together, being basically the following ones: 
In the first place, there are ten rectangular plates generally referred to 
with number (1) and whose configuration can be seen in FIGS. 1 and 2. They 
are considerably thick given that in the edges thereof the peripheric 
groove (2) is made for partial insertion of the rectangular boards (3) and 
(4), used for coplanar connection between juxtaposed plates (1). 
Each one of these rectangular plates (1) has ten perpendicular dowels (5) 
whose top end is recessed in order to facilitate insertion of other parts 
comprising the toy, specifically those shown in FIGS. 3 to 9. 
In FIGS. 3 to 9 we can see the thinner plates represented that define some 
of the digits and that are superimposed and that fit in the dowels (5) of 
the rectangular plates (1). In FIG. 3 we can see a perspective partial 
view of one of these thinner plates, generally referred to as number (6) 
and that has short stepped cylindrical protuberances (7) in the top face 
thereof, according to a distribution in accordance with the number that 
they represent, having a through hole (8) with a diameter adapted to that 
of the widenened portion of the dowels (5) of the rectangular plates (1) 
that are used as a base for formation and juxtaposition of plates (6), 
facilitating the fitting together upon the stepping being of the truncated 
cone-shaped type. Hence, in FIGS. 4 to 6 plates (6) that correspond to the 
digits one, two and four are shown, having a total surface proportional to 
the number that they represent. FIG. 7 shows the formation of the number 
"seven" simply by adding the number "one" to the number "six" with the 
help of the assembly part (9). 
In FIG. 8 we can see a plate with cylindrical protuberances (7) that 
correspond to a ten. In order to facilitate the counting of the number of 
stepped cylindrical protuberances (7) that these plates have, every four 
protuberances (7) that exist according to the vertexes of a square, are 
grouped by an intermediate hollow space (10). The cylindrical 
protuberances (7) are distributed in two rows of five. The last pair is 
related by a generally rectangular shaped recess or hollow space (11). 
In FIG. 9 we can see the cross section of the plates (6) where the stepped 
cylindrical protuberances (7) have a step that determines the formation of 
an end portion (12) with a smaller diameter, tight fit in the cylindrical 
recess (13) existing in the bottom face of the plate (14), thus allowing 
the stacking of this type of digital plates (6). 
In FIG. 10 a transparent template (15) that has ten circular orifices (16) 
has been shown. 
As we have indicated at the beginning of this specification, the different 
elements comprising the didactic-educational toy for elementary arithmetic 
operations, have different colors, or else, they have a perimetric strip 
of a different color. Some of them may also be made out of a transparent 
material or may have a different contour. Hence, the plates (1) with 
dowels (5) are green; the rectangular boards (3) and (4) to assemble 
different plates (1) are red; the perimetric strip of the transparent 
templates (15) is red and is referred to as number (18), just like the 
plate with dowels (6) that corresponds to the number "ten." 
In FIG. 12 we can see the figurative pieces that can be assembled in the 
grooves (2) of the plates with dowels (1), just like the red rectangular 
boards (3) and (4) (see FIG. 1), with which drawings can be formed, in 
this case a toy airplane and as we have said before they allow the study 
of spatial concepts of left, right, up and down, as well as stimulating 
the child's oral expression upon problematic situations being posed. These 
figurative pieces are generally referred to as number (19). 
FIG. 13 shows an operative example in which "nine", plus "four" plus 
"seven" have been added up. For this purpose the thin plate (6) with nine 
stepped cylindrical protuberances (7) has been used, inserting the 
different addends upon two plates with protuberances (1). The first addend 
is in turn obtained upon adding the one to the number "eight", by means of 
a small plate (20) which we will discuss later on in connection with FIG. 
14. The addend "four" is previously obtained by joining to number "two" 
the representative number of the one on both sides, which is done with the 
help of other small retention plates. The different plates (6) have a blue 
perimetric strip and as two groups of ten have been completed, the 
transparent templates (15) that have a red perimetric strip (18) are 
inserted in them. 
Referring to FIG. 7 once again, we can see that the assembly parts (9) join 
the blue stepped cylindrical protuberances (7) and they allow replacement 
of the special templates of even numbers to be joined with the uneven 
ones, replacing for example the center addend "four" of FIG. 13. The 
uneven number templates can also be replaced given that it suffices to add 
the number "one" to the preceding even number. 
The digital plates (6) have a blue perimetric strip (17), as identification 
of the ones. Upon adding "six+one" (see FIG. 7), the assembly part (9) 
hides the perimetric strip (17) that corresponds to the connection area, 
thus offering only the perimetric strip of the number that identifies the 
sum. 
In FIG. 3, as well as in FIG. 9, we can see the small elongate notches, 
distributed in pairs and diametrically opposite in two perpendicular 
diameters referred to as (21), to immobilize the assembly parts (9), 
provided for this purpose with small bulges (22). 
The transparent templates (15) of FIG. 10, aside from being used to 
surround the tens that arise upon working, serve as operation bases (with 
the same function as the green plates with dowels (1)), the stepped 
cylindrical protuberances (7) of the digital plates (6) inserting in the 
circular orifices thereof (16). By means of a red board, whose dimensions 
can coincide with the rectangular board (4) for coplanar connection of 
different plates with dowels (1), the formation of tens can be identified, 
placing them in an inserted manner between the stepped cylindrical 
protuberances (7). 
Now making special reference to FIG. 11, we can see with reference number 
(23) the plate with ciphers that includes some recesses or slots (24) made 
on the surface thereof. The suitable template with stepped cylindrical 
protuberances (6) that correspond to the contour thereof would fit in 
them, to identify the extension of the number with its shape. There are 
hollows (25) on two sides of these recesses (24) to facilitate the lifting 
of the inserted plates (6). A circle (26) containing the groove (27) of 
the shape and the mnemonic drawing thereof is drawn on the top part. This 
groove (27) defines a path that will be followed by the pencil or scriber 
starting from an initial red point (28), facilitating automatization and 
correct tracing of the shape before writing it. 
In a basic option, the types of parts that would be needed to be able to 
work would be: 
--Plates (6) with numbers "one," "two," "four", "six", "eight" and "ten." 
The anchoring parts (9) allow manufacturing to be reduced to numbers 
"one," "two" and "four." 
--Anchoring parts (9), which may also be double to simultaneously join the 
two rows of digital plates (6). 
--Transparent templates (15). 
--Red boards to join the plates with dowels (1) and to make the tens upon 
fastening them between the stepped cylindrical protuberances (7). 
--Rectangular plates with ciphers (23). 
--Rigid and articulated pincers. 
To work with hundreds and in order to be able to represent this 
mathematical concept it has been provided for that the bottom face of the 
digit "ten" of the plates (6) or some transparent templates (15), have a 
perimetric green strip (colors that indicate the formation of the 
hundred). Several green colored elongate boards could be used for this 
purpose. Making the modifications of the first two parts, the logical 
acceptance thereof would be had given that upon the number "ten" nine 
other plates can be stacked and the hundred would be formed. 
Now making special reference to FIG. 14 we can see with reference numbers 
(20) the rectangular small plates that can be used to replace the assembly 
parts (9), in the event that the latter might represent a danger for the 
small player, due to the small size thereof and due to the fact that they 
are open. These little plates (20) have circular orifices (16) for 
insertion in the stepped cylindrical protuberances (7). The dimensions of 
these rectangular small plates are such that they do not manage to cover 
the colored peripheral edge (17), in the connection area, in the event 
that these parts are white or opaque, although they may also be 
transparent in order to see the break-up of a number. Making reference to 
this FIG. 14, the operation "four+three", we can see that in a first 
option these digital plates (6) have been inserted in a transparent 
template (15) without the need to use the green plate with dowels (1). 
Using the rectangular small plates (20), or else, similar assembly plates 
(29) but with a double number of orifices (16), the transparent templates 
(15) can be omitted, operating in the following manner: 
The first addend, plate "four", to which the little assembly plate (29) is 
coupled in its protuberances, is used, advancing in the direction 
indicated by the arrows, thus orifices (16) thus inserting in the stepped 
protuberances (7), the unit fitting in perfectly. Then, one proceeds in 
the same way with the rest of the addends, the blue fringe sections, 
contiguous to the two addends, remaining hidden. Finally, a transparent 
template (15) with a red perimetric strip, or a red board will be inserted 
to indicate that a group of ten has been formed. 
These anchoring plates (20), opaque ones (29) are important because this 
presupposes the progressive visualization of partial sums, eliminating 
blue sections and above all because with few types of digital plates (6) 
the remaining digits can be formed, without the need to be manufactured, 
as is seen in FIG. 13. 
In FIGS. 15 to 17, with reference number (30) there are the thicker digital 
plates, whose thickness coincides with that of the plates with dowels (1) 
and that also have a perimetric groove (31). The stepped cylindrical 
protuberances (7) can have an alternative construction, with some 
diametric cuts to make the fitting together more elastic, as well as two 
circular grooves (32) with points with a greater widening to collaborate 
in the fastening of the assembly parts (9) and articulating parts which we 
will discusss later on. A single transversal cut would also be made in the 
stepped cylindrical protuberances, but they must turn one in terms of the 
other and on the base of the plate. 
In the reverse of these plates (30) there is a ring or annular embossment 
(33) and a concentric groove (34) (see FIG. 17). The plates (30) have in 
their end opposite the one where there is the annular embossment (33), 
another annular groove (35) concentric to and interior to the groove (34), 
thus allowing the assembly of two plates (30) by their reverse, upon the 
ring (33) and the annular groove (35) having the same diameter. 
In FIG. 15 we can specifically see, a plate (30) with a perimetric groove, 
corresponding to the number "two." The small rectangular recesses 
symmetrically distributed along the contour thereof are referred to as 
number (36). 
Reference (37) of FIG. 15 designates the independent tongue pieces that are 
used for the juxtaposition of plates (30), the latter having recesses (38) 
of the same geometric shape as the tongue pieces in order to immobilize 
them. 
The annular groove (34) concentric to the cylindrical protuberances (7) of 
the bottom face of the digital plates (30) is used for the coupling of the 
articulating parts that allow the plane to be changed and allow geometric 
shapes in space to be formed, for use thereof in constructions. We can see 
these articulating parts mainly in FIGS. 18 to 21 and they are generally 
referred to as number (39). They include two complementary parts 
interconnected as a hinge, referred to as (40) and (41), coupling by means 
of the articulating heads formed by two components integral to the 
respective element, referred to as (42) and (43). The articulating parts 
(39) have rings (44) in each one of their limbs or parts, materializing 
the means of connection to the digital plates (30), upon tightly fitting 
in the annular groove (35) of the reverse of the same and the articulating 
heads fitting in the peripheral recesses (36). As it can be inferred from 
observing FIG. 17, the diameter of the annular form of the groove (34), 
coinciding in turn with that of the rings (44) of the articulating parts 
(39) is identical to that of the larger dimension of the stepped 
cylindrical protuberances (7), which permits tight insertion, assisted by 
the existence of the small diametrically opposite protuberances (45), that 
fit in the circular recesses or grooves (32) of said cylindrical 
protuberances (7) (see FIG. 17). 
The articulating parts (39) also include some flexible tongue pieces (46) 
that faciliate disassembly, since the protuberances or bulges (45) 
sufficiently adjust pieces (40) and (41) in the circular grooves (32) of 
the stepped cylindrical protuberances (7). 
Making special reference to FIG. 21 we can see in it and on a larger scale, 
the geometric shape that the components (42) and (43) of the articulated 
head of the articulation pieces (39) have. Component (42) acts as the male 
element and has two cylindrical portions (47) and (48) with different 
lengths. On its part, component (43) has two partition walls (49) with a 
general semi-circular contour and that emerge perpendicularly from a rear 
wall (50), in turn perpendicular to the plane of the wall or sheet (41) of 
the part of the articulating head in which it is found. 
There are some arched paths (51) and other straight ones (52) on the inside 
surface of the walls or partition walls (49) and these straight walls open 
to the outside. The cylindrical portions (47) and (48) of the joint 
component (42) are introduced along the straight path (52), until the ends 
of the cylindrical portion (47) are introduced into the respective 
housings (53) that limit the straight path (52), in such a way that the 
cylindrical portions (48) remained aligned up with the arched path (51), 
which allows rotation 90.degree. in either direction, there being 
intermediate positions at 45.degree., all of them marked by convenient 
widenings of the arched path (51), as it is simply inferred from observing 
FIG. 21 which we are now referring to. 
One of the red boards that allowed the formation of a group of ten to be 
marked, upon remaining fit tight between the stepped cylindrical 
protuberances (7), referred to as number (54), can be seen partially in 
FIGS. 22 and 23. As a special characteristic it has the fact of including 
a perimetric groove and a recess in one of the faces thereof to serve as 
location and slightly fastening the little plate (6) corresponding to 
number "one." Its flexibility allows this card to capitulate upon 
exercising an extreme action just as it is inferred from observing this 
figure (23). This characteristic applied to a game of knocking down some 
vertical targets that occupy a raised position is also seen in FIG. 29. 
As we said at the beginning, the parts representative of half of the unit, 
whose geometric shape is shown in FIG. 24 and which corresponds to an 
isosceles right-angled triangle, referred to as (55) are taken advantage 
of in constructions. In FIGS. 25 and 26 we can see how the coupling of 
some pincers (56) to the digital plates (6) is done, upon having a 
cylindrical stub (57) that can be inserted in the bottom cylindrical 
opening of the thin digital plates (6). The pincers (56) have as a special 
characteristic with relation to the rigid pincers (58) of FIG. 2, the fact 
that they are articulated to allow the plane to be changed, just as it is 
seen more clearly in the example shown in FIG. 29. 
In FIG. 27 we see another configuration of pincers, generally referred to 
as number 59, being fastened to the plates with a perimetric groove on the 
edge thereof, upon having a sheet-like extension (60) provided with small 
bulges for pressure insertion inside the perimetric groove of the plates 
(30). 
In FIG. 28 we see an embodiment that can be encouraging for a child, if he 
is awarded something upon being able to make the figure of a truck will 
all of the addends. 
In FIG. 39 the knock-down toy that we have commented on before in 
connection with the use of the flexible red boards (54) is represented. 
Other geometric bodies and figures that can be obtained with this type of 
toy are shown in FIGS. 30 and 31. 
Finally, in connection with FIGS. 32 and 33 we can see the use of the 
invention for learning how to read and write, for which we had indicated 
that there were parts comprising a second group of cards. There are cards 
(61) of a different contour and color for consonants and vowels, all of 
them having on one of their side faces a dovetail-shaped tongue piece (62) 
and on the opposite face a groove (63), these elements that define the 
grooved-tongued interconnection means for forming words just as it is 
shown in the top part of this FIG. 33. 
The letter cards (61) also have on the top or viewed face a pair of 
horizontal protuberances (64) in correspondence with the horizontal 
grooves (65) of the bottom face, thus allowing the centered stacking. 
The letter cards (61) can be linked together directly to form words, or 
else, each one of them can be put inside the molds (66) with a rectangular 
contour identical in all of them, though there are window-type recesses 
(67) inside them where the letter cards (61) can be placed. These recesses 
(67) correspond with the geometric shape that said letters have depending 
on the type of lettering, as in seen in this FIG. 33. The recesses or 
windows (67) have a contour oversized with regard to the letter cards 
(61), thus allowing the contour thereof to be marked upon passing the tip 
of a pencil through the path formed, just as it is shown with number (68) 
in FIG. 32. The tongue piece (62) that the letter cards (61) have is 
housed in the dihedral recess (69) of the mold (66), these elements (62) 
and (69) having a dovetail contour to keep the correct position of the 
letter cards (61) with regard to the window (67) immobile. The molds (66) 
have some side wings (70) and grooves (71) facing each other, for coplanar 
coupling thereof just as it has been indicated for the letter cards (61). 
These molds (66) also have other wings (72) placed in the top part for 
connection of the mold to the digital plates (30), upon being introduced 
in a tight manner in the perimetric groove of the same, as shown in the 
bottom part of FIG. 32. Thus, words that can be separated by hollow 
spaces, or else, by means of a blank mold or with a graphic point as 
referred to as (73) in FIG. 32. 
On the top face of the molds (66) and close to the top wing (72), there is 
a horizontal protuberance (74) facing another groove (75) made in the 
bottom face, thus allowing stacking. 
On the top edge of the alignment of digital plates (30) with a perimetric 
groove, just as is indicated in FIG. 32, there are other cards (76) that 
have on both faces the contour of the letters that make up the words that 
in turn correspond with the allegorical drawing that appears on the top 
part of the card. On the opposite or reverse face, there is also the same 
allegorical drawing and the entire word written. In FIG. 32 the cards (72) 
that occupy the first and third space have the word written, corresponding 
to the obverse side of the card, while those that occupy the second and 
fourth space offer the reverse side because they only show the contour of 
the types of letter (vowel or consonant), of the word. The cards (76) are 
fastened with the help of pincers and any of the types commented on above 
may be used. 
In FIG. 33 the details corresponding to the bass-relief that defines the 
shape of each one of the letters of the cards (61) have been shown in a 
larger scale, with a deeper hollow in the bottom of channel (73) so that 
the student achieves a perfect tracing of the letter and can then produce 
it on paper, once the rectangular or circular contour of the different 
letters of the words that make up of the sentence has been drawn, just as 
it is shown in FIG. 32. The tracing direction in italics is determined and 
symbolized by: colored strips (78), with a thinner intermediate groove and 
a double arrow that indicates arrival, backward motion and the fact that 
the pencil or scriber is not to be raised. 
In order to facilitate removal of the letter cards (61) from the window 
(67) of the mold (66), the same have recesses (79) in opposite areas of 
the periphery thereof, in which one's nails are introduced.