Abstract: The Thread Ruler and Multi-Function Drafting Instrument is a single instrument designed to draw circles, ellipses and parallel lines, and which includes features that allow the instrument to function as protractor, a ruler and a drawing compass. The instrument has a slide ruler that holds a marking device and that has a stem with a thread attached. The thread is further attached to the main ruler body at an outer end of the protractor so that ellipses can be drawn. The instrument may be used on any flat marking surface including: paper, drafting table, chalkboard and dry erased board. The instrument may be adapted to be used in portable manner so that it can be placed in shirt pocket.

Abstract: This device facilitates field marking an arc of a circle having an obstructed center. It comprises a first clamp having a slot to engage a standard tape measure and a second clamp having another slot to engage a color-coded tape measure. A detachable swivel joint snap connects the first clamp to the second clamp, and a handle is connected to the first clamp. A method is provided to use the device, a standard tape measure, a color-coded tape measure, a rod, and a scribe to mark out such an arc. The method comprises identifying coordinates of an eccentric ellipse, whose foci are field accessible, that will substantially overlap the arc. The two tape measures are anchored to the two foci. The standard tape measure is stretched tight between the two foci while the color-coded tape measure provides a string line for marking out a closely fitting elliptical arc segment.

Abstract: Disclosed is an ellipsograph for drawing an ellipse. A base member for defining one side, that is, a base of a triangle, is provided and fixed to a plane of a drawing sheet. A centering section and an ellipse drawing frame are installed at a middle of the base member. An ellipse deriving thread for determining the total length of three sides of the triangle which is used to draw the ellipse is prepared and supported by both ends of the base member and one end of the ellipse drawing frame thereby to form the triangle. The ellipse is drawn by the ellipse drawing frame while the ellipse drawing frame is rotated and linearly reciprocated due to the fact that the ellipse drawing frame is pressed by the ellipse deriving thread against elastic force of elastic spring and biased by the elastic spring against tension of the ellipse deriving thread.

Abstract: The present invention provides a variety of laminated plastic activity boards that allow the individual to visualize and have interactive exploration of conic sections and their definitions. This allows for more class time to be spent investigating the concept of conic sections opposed to teachers lecturing and the students having to memorize them. The user is able to notice patterns which develop while drawing specific sets of conic sections by forming conjectures based on the observed outcomes of the activities. Each activity board has a reusable laminated surface which allows the ink used from a marker to be visible but not permanent. The surface can be wiped clean with a moist paper towel once the activity is completed. There are a total of four activity boards which operate independently of each other and contain different concepts. The four boards teach principles relating to the circle, ellipse, parabola and hyperbola.