Geometrical instruments – Straightedge type – Rules
Reexamination Certificate
1998-04-14
2001-02-27
Fulton, Christopher W. (Department: 2859)
Geometrical instruments
Straightedge type
Rules
C033S679100, C434S196000, C434S188000
Reexamination Certificate
active
06192594
ABSTRACT:
BACKGROUND OF THE INVENTION
The use of teaching devices to teach and learn the concepts behind and mathematical operations involving fractions, mixed numbers and decimals are known. With some such devices the measurement of fractional lengths by the use of rulers of various kinds is employed.
The present invention relates to one such ruler wherein a triangular shaped prism with three faces has twelve scaled working edges. Four scaled working edges are located on each prism face with two such edges being adjacent each other along one of the prism's three edges. The length of the prism's edge is at least twice that of two of the adjacent scaled working edges, scaled numbers appear on different prism faces having a common prism edge and are inverted from each other. This permits a user to use a common prism edge against a paper or suitable drawing surface with the desired scale against the surface. A reference mark on the surface from one of the scales can easily be interrelated to other scales by turning the prism over to show those scales.
DESCRIPTION OF THE PRIOR ART
Patented devices for teaching the concepts and use of fractions are well known. For example, in U.S. Pat. No. 356,167 to Shannon sets of cards or blocks with color coded numbers for each set representing different values are used. A card or block representing unity is proportionally divided by the different fractional values.
In the Pannenkowa reference (U.S. Pat. No. 1,098,330) the understanding of numerators and denominators used in fractions plus the principles of their simplification is disclosed using sliding plates mounted between parallel battens in a frame.
The Coleman reference (U.S. Pat. No. 1,174,689) describes a series of card supporting horizontally disposed wires with a series of similarly disposed staggered rods.
An easel support jumbo ruler is used in the Struna (U.S. Pat. No. 2,803,069) invention and is made up of different movable block units representing different fractions.
The McMeen patent (U.S. Pat. No. 3,204,344) discloses a wheel and stick wherein number to be divided is represented by the stick and the fraction by which it is divided is represented by a wheel.
The Marsh et al represents (U.S. Pat. No. 3,781,114) describes an angular position indicating system of a continuously rotating member with a counter and wherein the ratio of the instantaneous count of the counter to a total count is equal to the ratio of the angular position of a stepping motor to 360 degrees.
Maurer's invention (U.S. Pat. No. 4,614,042) discloses a ruler is divided by subdivisions having both visual indicia and tactile features.
Marans's invention (U.S. Pat. No. 4,778,390) different fractional scales with a defined space or gap between the scales permits the insertion of a a piece of paper.
In the Sher invention (U.S. Pat. No. 5,470,234) a circular piece matching math educational aid is disclosed. The present invention provided for a triangular shaped prism having different scaled fractions appearing in groups of two aligned number sets of two different scales on one side of each of the triangle's three faces all as more further set forth in this specification.
SUMMARY OF THE INVENTION
This invention relates to an educational apparatus to teach and learn the concept of mathematical operations using fractions. A triangular prism with different number scales thereon is employed in this educational tool.
It is the primary object of the present invention to provide for an improved apparatus to teach and learn fractions, mixed numbers and decimals.
Another object is to provide for such an apparatus utilizing a one piece tool resembling a ruler.
These and other objects and advantages of the present invention will become apparent to readers from a consideration of the ensuing description and the accompanying drawings.
REFERENCES:
patent: 356167 (1887-01-01), Shannon
patent: 679599 (1901-07-01), Cambell
patent: 1098330 (1914-05-01), Pannenkowa
patent: 1174689 (1916-03-01), Coleman
patent: 1356987 (1920-10-01), Ingle
patent: 2803069 (1957-08-01), Struna
patent: 3204344 (1965-09-01), McMeen
patent: 3781114 (1973-12-01), Marsh et al.
patent: 4614042 (1986-09-01), Maurer
patent: 4778390 (1988-10-01), Marans
patent: 5470234 (1995-11-01), Sher
Extra Measures, Inc.
Fulton Christopher W.
Laff Whitesel & Saret
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