CN214727756U

CN214727756U - Telescopic multifunctional teaching aid

Info

Publication number: CN214727756U
Application number: CN202120927205.XU
Authority: CN
Inventors: 邹涛; 刘健; 姜博鑫
Original assignee: Zhijiang College of ZJUT
Current assignee: Zhijiang College of ZJUT
Priority date: 2021-04-30
Filing date: 2021-04-30
Publication date: 2021-11-16
Anticipated expiration: 2031-04-30

Abstract

The invention discloses a telescopic multifunctional teaching aid, which comprises a main support shaft, a main scale, a middle scale, an inner scale and an auxiliary scale, wherein one ends of the main scale and the auxiliary scale are respectively and rotatably arranged on the main support shaft, and the top of the auxiliary scale is provided with reference circle scale lines around the main support shaft; the middle ruler is telescopically arranged in the main ruler, and the inner ruler is telescopically arranged in the middle ruler; the rear side surfaces of the main ruler, the middle ruler and the inner ruler are continuously provided with chalk clip sliding grooves, and chalk clips are slidably arranged in the chalk clip sliding grooves. The ruler is simple and small in structure, avoids teachers from carrying a plurality of teaching tools, reduces the time for the teachers to frequently change tools for blackboard drawing, reduces the difficulty of the teachers in carrying the teaching tools for class, is convenient to carry by stretching and contracting the ruler, and also ensures the basic drawing size requirement during teaching.

Description

Telescopic multifunctional teaching aid

Technical Field

The invention relates to the technical field of teaching tools, in particular to a telescopic multifunctional teaching aid.

Background

Most of blackboard drawing tools used in the existing teaching process are compasses, rulers, protractors and the like which are separated independently, and the drawing tools have the defects of overlarge size, excessive types and the like, are inconvenient for teachers to carry about, have large occupied space and are inconvenient to store. When teachers draw pictures in teaching, compasses, rulers, protractors and the like need to be frequently replaced, operation is inconvenient, and teaching speed is reduced.

The prior art also has multifunctional teaching rulers, but the teaching rulers are too complex and difficult to manufacture; or the functions are various but the sizes are large, so that teachers are inconvenient to carry about to enter all classrooms; or the size is small, and the requirement of daily teaching drawing is not met. Therefore, a multifunctional teaching aid is urgently needed to be developed, and is convenient for teachers to use in classroom.

Disclosure of Invention

The invention aims to provide a telescopic multifunctional teaching aid, which aims to solve the problems in the prior art in the background technology.

In order to achieve the above purpose, the invention provides the following technical scheme:

a telescopic multifunctional teaching aid comprises a main support shaft, a main scale, a middle scale, an inner scale and an auxiliary scale, wherein one ends of the main scale and the auxiliary scale are respectively and rotatably arranged on the main support shaft, the top of the auxiliary scale is provided with reference circle scale marks around the main support shaft, one sides of the main scale, the middle scale and the inner scale are provided with continuous scales, one side provided with scales is defined as a rear side, and the other side of the main support shaft is defined as a left side;

the middle ruler is telescopically arranged in the main ruler, and an installation angle cover is arranged at the upper right front corner of the opening end of the main ruler; a chamfer surface beta surface is arranged on the front upper side of the middle ruler along the length direction, and an inclined surface alpha surface is continuously arranged obliquely upwards at one end of the beta surface close to the main support shaft; the inner side of the mounting angle cover is provided with a beta ' surface matched with the beta surface, and one side of the beta ' surface, which is close to the main support shaft, is provided with an inclined alpha ' surface corresponding to the alpha surface in an inclined and upward manner; the left end of the middle ruler body is formed with a connecting section of which the rear side and the bottom surface are lower than the middle ruler, a transition slope is arranged at the connecting part of the connecting section and the middle ruler body, and the right end surfaces of the rear side and the bottom side of the main ruler are matched with the transition slope; when the middle ruler slides in the main ruler, the beta surface is attached to the beta' surface; when the middle ruler extends outwards, the alpha surface and the alpha' surface are matched to enable the middle ruler to move downwards, backwards and rightwards until the bottom surface and the rear side surface of the middle ruler are respectively flush with the bottom surface and the rear side surface of the main ruler; the right end of the main scale is provided with a locking screw for locking the relative position of the middle scale and the main scale;

the inner ruler is telescopically arranged in the middle ruler, and the connecting structure of the inner ruler and the middle ruler is the same as that of the middle ruler and the main ruler;

the chalk clip sliding groove is continuously formed in the rear side surfaces of the main ruler, the middle ruler and the inner ruler, and the chalk clip is slidably arranged in the chalk clip sliding groove.

Preferably, a positioning groove is formed in the position, close to the right end, of the rear lower corner of the main ruler, and a positioning bump matched with the positioning groove is arranged on the rear lower corner of the connecting section of the middle ruler; the left sides of the positioning groove and the positioning lug are inclined planes; when the middle ruler is in an extending state, the positioning lug is embedded into the positioning groove.

Preferably, the outer contour of the positioning lug is flush with the outer contour of the middle ruler.

Preferably, the outer contour of the installation angle cover is flush with the outer contour of the main ruler, the rear side and the lower side of the installation angle cover are respectively provided with a plug board, and the main ruler is correspondingly provided with a plug groove, so that the plug board of the installation angle cover can be inserted into the plug groove from the right end of the main ruler.

Preferably, a boss is arranged at the right end of the upper surface of the main ruler, the boss is provided with a threaded hole which penetrates through the boss up and down, and the locking screw is in threaded matching with the threaded hole; and the plug board at the rear side of the mounting angle cover is provided with a through hole for the locking screw to pass through.

Preferably, the upper surface of the middle ruler is provided with locking counter bores which correspond to the extending state and the contracting state respectively.

Preferably, a lifting shaft mounting hole which is communicated up and down is formed in the main support shaft along the axial direction, and a lifting shaft is arranged in the lifting shaft mounting hole; the lifting shaft is in threaded fit with the upper part of the lifting shaft mounting hole, and is in clearance fit with the lower part of the lifting shaft mounting hole; the bottom of lift axle is equipped with the magnet frame, be equipped with first magnet in the magnet frame.

Preferably, an auxiliary support shaft capable of moving up and down is arranged at the free end of the auxiliary ruler in a penetrating mode, a second magnet is arranged at the bottom end of the auxiliary support shaft, and a limiting nut is arranged at the top end of the auxiliary support shaft; and a counter bore corresponding to the second magnet is formed in the upper surface of the main scale, and a third magnet is arranged in the counter bore.

Preferably, a strip-shaped groove is formed in the middle of the auxiliary ruler along the length direction; the main scale is provided with an alignment line, and when the auxiliary scale is superposed with the main scale, a 0-degree scale line of the auxiliary scale is superposed with the alignment line; the right end of the inner ruler is provided with a V-shaped groove.

Preferably, the chalk clamp comprises a chalk clamp body, a clamping screw and a sliding block, the sliding block is fixed on the chalk clamp body, and the sliding block is matched with the chalk clamp sliding groove; the chalk clamp body is of a two-ear opening type hoop structure, holes are formed in two ears of the chalk clamp body respectively, and the clamping screws penetrate through the holes in the two ears of the chalk clamp body to be fastened.

Compared with the prior art, the invention has the advantages that: the blackboard drawing tool is simple and small in structure, avoids a teacher from carrying a plurality of teaching tools, reduces the time for the teacher to frequently change tools in the blackboard drawing, and reduces the difficulty of the teacher carrying the teaching tools for class; meanwhile, the ruler is convenient to carry by stretching, the basic drawing size requirement during teaching is also ensured, and the scale ends of the ruler can be kept flush after stretching; by arranging the supporting shaft lifting mechanism, friction between the straight ruler and the blackboard during circle drawing is avoided, and circle drawing is easily achieved; the accurate angle can be drawn through the auxiliary ruler; set up the posture when slidable chalk clip not only changed blackboard drawing circle in the past, more laborsaving, the chalk can remove about on the chi, can draw the circle of different diameters to effectively replace drawing instrument in the past.

Drawings

Fig. 1 is a schematic view of the overall structure of the present invention.

Fig. 2 is an exploded schematic view of the present invention.

Figure 3 is a schematic detail (forward) view of the main and middle ruler ends of the present invention.

Fig. 4 is a schematic view (back direction) of the main and middle ruler end portions of the present invention.

Fig. 5 is a schematic view of the fitting details of the bezel of the present invention and at B in fig. 2.

Fig. 6 is a schematic diagram of the invention in the detail of the fit at a and B in fig. 2.

FIG. 7 is a partial cross-sectional view of the main support shaft of the present invention.

Fig. 8 is an expanded schematic view of the teaching aid of the present invention.

Fig. 9 is a schematic view of the angle drawing structure of the present invention.

In the figure: 1. a main scale; 2. a middle ruler; 3. an inner ruler; 4. mounting a corner cover; 5. positioning a groove; 6. positioning the bump; 7. a plugboard; 8. inserting grooves; 9. a boss; 10. locking the screw; 11. locking the counter bore; 12. a chalk clip sliding groove; 13. a chalk clip; 14. a chalk holder body; 15. a clamping screw; 16. a slider; 17. a lifting shaft; 18. a magnet frame; 19. a first magnet; 20. a secondary ruler; 21. a main support shaft; 22. a secondary support shaft; 23. a second magnet; 24. a limit nut; 25. a counter bore; 26. a strip-shaped groove; 27. aligning the lines; 28. and a V-shaped groove.

Detailed Description

In the description of the present invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

Referring to fig. 1-9, a telescopic multifunctional teaching aid comprises a main support shaft 21, a main scale 1, a middle scale 2, an inner scale 3 and an auxiliary scale 20, wherein one end of the main scale 1 and one end of the auxiliary scale 20 are respectively and rotatably arranged on the main support shaft 21, the main scale 1 is arranged below the auxiliary scale 20, the auxiliary scale 20 is arranged above the main support shaft 21, a circle of reference circle scale marks are arranged at the top of the auxiliary scale 20 around the main support shaft 21, continuous scales are arranged on one side of the upper surfaces of the main scale 1, the middle scale 2 and the inner scale 3, the direction shown in fig. 2 is used as a reference in the implementation, one side where the scales are arranged in a definition mode is a rear side, and one side where the main support shaft 21 is located is a left side.

In the structure, be equipped with right-hand member open-ended cavity in main scale 1 and the well chi 2, well chi 2 sets up in main scale 1 telescopically, and interior chi 3 telescopically sets up in well chi 2, through the overall length of the extension ruler of well chi 2 and interior chi 3 to can reduce the overall size of teaching aid after the shrink, portable and accomodate. The telescopic mechanism and principle of the inner ruler 3 in the middle ruler 2 are consistent with those of the middle ruler 2 in the main ruler 1, and the embodiment only takes the telescopic mechanism and principle of the middle ruler 2 in the main ruler 1 as an example for explanation.

In the embodiment, a gap is arranged at the upper right corner in front of the opening end of the main ruler 1, and an installation angle cover 4 is detachably arranged at the gap; a section of chamfer surface beta surface is arranged on the front upper side of the middle ruler 2 along the length direction, one end of the beta surface close to the main support shaft 21 is continuously provided with an inclined surface alpha surface towards the inclined upper side, and one end far away from the main support seat 21 is a limiting surface for limiting during contraction; the inner side of the mounting angle cover 4 is provided with a beta ' surface matched with the beta surface, and one side of the beta ' surface close to the main support shaft 21 is provided with an inclined alpha ' surface corresponding to the alpha surface in an inclined and upward manner; the left end of the ruler body of the middle ruler 2 is formed with a connecting section d with the rear side and the bottom surface lower than the middle ruler 2, the connecting part of the rear side surface and the bottom surface of the connecting section d and the ruler body of the middle ruler 2 is respectively provided with a transition slope delta surface and an epsilon surface, and the rear right end surface delta 'surface and the bottom right end surface epsilon' surface of the main ruler 1 are also inclined surfaces and are respectively matched with the transition slope delta surface and the epsilon surface; the rear lower corner of the main ruler 1 is provided with a positioning groove 5 close to the right end, the rear lower corner of the connecting section of the middle ruler 2 is provided with a positioning lug 6 matched with the positioning groove 5, the left sides of the positioning lug 6 and the positioning groove 5 are inclined planes which are respectively a gamma plane and a gamma' plane, and the external contour of the positioning lug 6 is flush with the external contour of the middle ruler 2.

In the structure, the outer contour of the installation angle cover 4 is flush with the outer contour of the main ruler 1, the rear side and the lower side of the installation angle cover 4 are respectively provided with the inserting plate 7, the main ruler 1 is correspondingly provided with the inserting groove 8, so that the inserting plate 7 of the installation angle cover 4 can be inserted into the inserting groove 8 from the right end of the main ruler 1, the right end of the upper surface of the main ruler 1 is provided with the boss 9, the boss 9 is provided with a threaded hole which penetrates through up and down, and the threaded hole is internally provided with the locking screw 10 in a matching manner; a through hole for a locking screw 10 to pass through is formed in the plug board 8 on the rear side of the mounting angle cover 4, the inner diameter of the through hole is larger than the outer diameter of the locking screw 10, and the locking screw 10 can fix the position of the middle ruler 2 after passing through the threaded hole and the through hole in the plug board on the rear side of the mounting angle cover 4; preferably, the upper surface of the middle ruler 2 is provided with locking counter bores 11 corresponding to the extending state and the contracting state respectively, and when the middle ruler 2 is completely extended or completely contracted, the locking screw 10 is screwed to abut against the corresponding locking counter bores 11 to fix the position of the middle ruler 2.

When the middle ruler 2 is in a contraction state, the middle ruler 2 is positioned at the leftmost end in the main ruler 1, the upper, lower, front and rear four surfaces of the middle ruler 2 are attached to the inner cavity wall of the main ruler 1, and the beta surface is attached to the beta' surface; in the process that the middle ruler 2 extends outwards, the beta surface and the beta 'surface are kept in a fit state before the alpha surface contacts with the alpha' surface; when the alpha surface just contacts with the alpha 'surface, the gamma surface and the gamma' surface are positioned on the same plane but do not start to be attached, and similarly, the delta surface and the epsilon surface are respectively positioned on the same plane as the delta 'surface and the epsilon' surface but do not start to be attached; continuously pulling the middle ruler 2 outwards, and enabling the middle ruler 2 to move downwards, backwards and rightwards through the matching of the alpha surface and the alpha 'surface until the bottom surface and the rear side surface of the middle ruler 2 are respectively flush with the bottom surface and the rear side surface of the main ruler 1, wherein the positioning bump 6 is completely embedded in the positioning groove 5, the gamma surface and the gamma' surface are attached, the delta surface and the epsilon surface are respectively attached to the delta 'surface and the epsilon' surface, and the rear side surface and the bottom surface of the connecting section d of the middle ruler 2 are respectively attached to the inner wall of the rear side and the inner wall of the bottom side of the main ruler 1; and then the locking screw 10 is screwed down to abut against the locking counter bore 11 of the middle ruler 2 in a corresponding extending state, and the expansion of the middle ruler 2 is completed.

When the ruler needs to be contracted, the locking screw 10 is unscrewed, the middle ruler 2 is pushed to the left, the middle ruler 2 is pushed to move towards the left side from the front side to the left side by utilizing the relative sliding of the gamma surface and the gamma ' surface and the relative sliding of the delta surface and the epsilon surface with the delta ' surface and the epsilon ' surface respectively, meanwhile, the alpha surface is contacted with the alpha ' surface and generates the relative sliding until the beta surface is contacted and jointed with the beta ' surface, at the moment, the middle ruler 2 can not generate longitudinal displacement any more and only can move leftwards, the middle ruler 2 is continuously pushed leftwards to the leftmost end, then the locking screw 10 is screwed down to be abutted into the locking counter bore 11 on the middle ruler 2 in a corresponding contraction state, and the middle ruler finishes the contraction.

The telescopic structure and principle between the middle ruler 2 and the inner ruler 3 are the same, and the description is omitted in the embodiment.

In this embodiment, the rear side surfaces of the main scale 1, the middle scale 2, and the inner scale 3 are respectively provided with chalk clip sliding grooves 12, and after the straightedge is unfolded, the chalk clip sliding grooves 12 on the main scale 1, the middle scale 2, and the inner scale 3 can be connected into a straight line. A chalk clamp 13 is arranged in the chalk clamp sliding groove 12, the chalk clamp 13 comprises a chalk clamp body 14, a clamping screw 15 and a sliding block 16, the sliding block 16 is fixed on the chalk clamp body 14, and the sliding block is H-shaped and matched with the chalk clamp sliding groove 12; the chalk clamp body 14 is of a two-ear opening type hoop structure, holes are formed in two ears of the chalk clamp body 14 respectively, one hole is a threaded hole, the other hole is a unthreaded hole, the inner diameter of the threaded hole is smaller than the inner diameter of the unthreaded hole, an external thread matched with the threaded hole is arranged at the front end portion of the clamping screw 15, the clamping screw 15 penetrates through the unthreaded hole and then is connected with the threaded hole, a chalk can be clamped in the chalk clamp body 14, and the whole chalk clamp 13 can slide along the chalk clamp sliding groove 12.

In the embodiment, the main support shaft 21 is sequentially divided into an external thread section, a polished shaft section and a base from top to bottom, and the end part of the main scale 1 is sleeved on the polished shaft section and can freely rotate around the polished shaft section; the end part of the auxiliary ruler 20 is matched with the thread of the external thread section; the bottom of the base is provided with a cavity. A lifting shaft mounting hole which is communicated up and down is axially formed in the main supporting shaft 21, and a lifting shaft 17 is arranged in the lifting shaft mounting hole; the relative upper part of the lifting shaft mounting hole is provided with internal threads, the relative upper part of the lifting shaft 17 is provided with external threads, the lifting shaft 17 is in threaded fit with the relative upper part of the lifting shaft mounting hole, and is in clearance fit with the relative lower part of the lifting shaft mounting hole; a magnet frame 18 is arranged at the bottom of the lifting shaft 17, and a first magnet 19 is arranged in the magnet frame 18; the top of the lifting shaft 17 penetrates through the top of the auxiliary ruler 20 and is formed with a knob.

In the above structure, the rotation knob can move the lifting shaft 17 up and down through the internal thread of the mounting hole of the lifting shaft and the external thread of the lifting shaft 17, when the lifting shaft 17 is lifted to the limit position, the magnet frame 18 and the first magnet 19 are accommodated in the cavity at the bottom of the base of the main support shaft 21, and the bottom surface of the first magnet 19 is flush with the bottom surface of the main scale 1. When a circle needs to be drawn, a user holds the main support shaft 21, rotates the lifting shaft 17 to enable the lifting shaft to descend, further drives the magnet frame 18 to move downwards, then the first magnet 19 attracts the blackboard as a circle center, and at the moment, a gap exists between the bottom surface of the main ruler 1 and the blackboard to avoid friction between the bottom surface of the main ruler and the blackboard. After the circle drawing is finished, the lifting shaft 17 is rotated reversely to reset the circle drawing.

In this embodiment, the sub ruler 20 is used for angle drawing, a sub support shaft 22 capable of moving up and down is arranged at the free end of the sub ruler, a second magnet 23 is arranged at the bottom end of the sub support shaft 22, and a limit nut 24 is arranged at the top end of the sub support shaft; the upper surface of the main scale 1 is provided with a counter bore 25 corresponding to the second magnet 23, and preferably, a third magnet is arranged in the counter bore 25. In addition, a strip-shaped groove 26 is formed in the middle of the auxiliary ruler 20 along the length direction, and the strip-shaped groove 26 corresponds to a 0-degree scale mark; the main scale 1 is provided with an alignment line 27, and when the auxiliary scale 20 is superposed with the main scale 1, a 0-degree scale line of the auxiliary scale 20 is superposed with the alignment line 27; the right end of the inner ruler 3 is provided with a V-shaped groove 28.

When drawing an angle, a user firstly draws a straight line on a blackboard by using the main ruler 1, the main ruler 1 rotates around the circumference of the main supporting shaft 21, the user aligns the straight line on the blackboard through the strip-shaped groove 26 at the top of the auxiliary ruler 20, then the auxiliary supporting shaft 22 is stretched downwards to enable the second magnet 23 to be in contact with the blackboard, when the main ruler 1 and the auxiliary ruler 20 form the required angle, a point is drawn at the vertex of the V-shaped groove 28 at the right end of the inner ruler 3 by using chalk, then the auxiliary supporting shaft 22 is pulled upwards, the auxiliary ruler 20 is rotated to return to the zero position, the second magnet 23 at the bottom of the auxiliary supporting shaft 22 is embedded into the counter bore 25 at the top of the main ruler 1 and generates adsorption with the third magnet to avoid the detachment of the second magnet, and finally the drawn point is connected with one end point of the straight line by using the main ruler 1 to form the required angle.

The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A telescopic multifunctional teaching aid is characterized by comprising a main support shaft, a main scale, a middle scale, an inner scale and an auxiliary scale, wherein one ends of the main scale and the auxiliary scale are respectively and rotatably arranged on the main support shaft, the top of the auxiliary scale is provided with reference circle scale marks around the main support shaft, one sides of the main scale, the middle scale and the inner scale are provided with continuous scales, the scale mark side is defined as the rear side, and the main support shaft side is defined as the left side;

2. The telescopic multifunctional teaching aid as claimed in claim 1, wherein a positioning groove is formed in a position, close to the right end, of a lower rear corner of the main ruler, and a positioning projection matched with the positioning groove is formed in a lower rear corner of the connecting section of the middle ruler; the left sides of the positioning groove and the positioning lug are inclined planes; when the middle ruler is in an extending state, the positioning lug is embedded into the positioning groove.

3. The telescopic multi-functional teaching aid of claim 2, wherein the outer contour of the positioning lug is flush with the outer contour of the middle ruler.

4. The telescopic multifunctional teaching aid as claimed in claim 1, wherein the outer contour of the angle cover is flush with that of the main ruler, the rear side and the lower side of the angle cover are respectively provided with a plug board, and the main ruler is correspondingly provided with a plug groove, so that the plug board of the angle cover can be inserted into the plug groove from the right end of the main ruler.

5. The telescopic multifunctional teaching aid according to claim 4, wherein a boss is arranged at the right end of the upper surface of the main scale, the boss is provided with a threaded hole which penetrates up and down, and the locking screw is in threaded matching with the threaded hole; and the plug board at the rear side of the mounting angle cover is provided with a through hole for the locking screw to pass through.

6. A telescopic multifunctional teaching aid as claimed in claim 1 or 5, wherein the upper surface of the middle ruler is provided with locking counter bores corresponding to the extended state and the retracted state respectively.

7. The telescopic multifunctional teaching aid as claimed in claim 1, wherein a lifting shaft mounting hole which penetrates up and down is formed in the main support shaft along the axial direction, and a lifting shaft is arranged in the lifting shaft mounting hole; the lifting shaft is in threaded fit with the upper part of the lifting shaft mounting hole, and is in clearance fit with the lower part of the lifting shaft mounting hole; the bottom of lift axle is equipped with the magnet frame, be equipped with first magnet in the magnet frame.

8. The telescopic multifunctional teaching aid according to claim 1, wherein an auxiliary support shaft capable of moving up and down is arranged at the free end of the auxiliary ruler in a penetrating manner, a second magnet is arranged at the bottom end of the auxiliary support shaft, and a limit nut is arranged at the top end of the auxiliary support shaft; and a counter bore corresponding to the second magnet is formed in the upper surface of the main scale, and a third magnet is arranged in the counter bore.

9. The telescopic multifunctional teaching aid according to claim 8, wherein a strip-shaped groove is formed in the middle of the auxiliary ruler along the length direction; the main scale is provided with an alignment line, and when the auxiliary scale is superposed with the main scale, a 0-degree scale line of the auxiliary scale is superposed with the alignment line; the right end of the inner ruler is provided with a V-shaped groove.

10. The telescopic multifunctional teaching aid as claimed in claim 1, wherein the chalk clamp comprises a chalk clamp body, a clamping screw and a sliding block, the sliding block is fixed on the chalk clamp body, and the sliding block is matched with a chalk clamp sliding groove; the chalk clamp body is of a two-ear opening type hoop structure, holes are formed in two ears of the chalk clamp body respectively, and the clamping screws penetrate through the holes in the two ears of the chalk clamp body to be fastened.