A magnetic set of five enlarged drawing instruments — ruler, protractor, two triangles and compasses — for demonstration constructions on the classroom board in mathematics lessons.
The classroom instrument set is a kit of enlarged drawing instruments for demonstration work directly on the classroom board. It is used in mathematics and geometry lessons to construct straight, parallel and perpendicular lines, angles of a given size, circles and arcs, and to measure angles. The set works on any magnetic (metal) board, needs no additional fastening and no power supply.
The set holds 5 instruments made of impact-resistant plastic, with scales applied in contrast print that stays clearly visible from the back rows of the classroom. The demonstration ruler is 100 cm long with a scale division of 1 cm; the protractor covers a working range of 0 to 180° with a scale division of 1°; the triangle with 30° and 60° angles measures 40 × 50 cm and the triangle with a 45° angle measures 30 × 30 cm. Every instrument carries magnetic holders that keep it firmly on the metal surface and stop it sliding while lines are drawn. The classroom compasses come with two interchangeable holders that take school chalk or a board marker, so one instrument serves both a chalk board and a marker board.
The set includes a 100 cm demonstration ruler with a scale, a classroom 180° protractor with a holder, classroom compasses for chalk and marker, a classroom triangle with 30° and 60° angles (40 × 50 cm) with a holder, a classroom triangle with a 45° angle (30 × 30 cm) with a holder, a passport with a warranty card, and individual transport packaging. Magnetic holders are a part of the corresponding instruments and are not supplied separately; chalk and board markers are bought separately. The set is supplied ready for work and needs no assembly.
An instrument is placed against the board with its reverse side and pressed so that all magnetic holders make contact with the surface; a correctly fixed instrument does not shift under the pressure of the chalk. The ruler serves for segments of a given length, straight lines and the demonstration of units of length, while the triangles are used for standard angles, perpendiculars and parallel lines — the ruler is fixed as a guide and the triangle is moved along its edge. With the protractor, the central mark is aligned with the vertex of the angle and the zero division with one of its sides, and the value is read on the inner or outer scale. For the compasses, chalk or a marker is clamped in the holder with a projection of 10 to 20 mm, the radius is set by spreading the legs and the hinge lock is tightened, and the circle is drawn in one continuous movement.
The magnetic holders create a permanent magnetic field, so the instruments are kept 10 cm away from bank cards, key cards, magnetic media, mechanical watches and hearing aids, and 30 cm away from pacemakers and other implanted medical devices; magnetic elements are kept away from children, since swallowing a magnet is life-threatening. The corners of the triangles and the leg of the compasses are pointed, so instruments are carried with the point towards the floor. Surfaces are wiped with a dry or slightly damp soft cloth and then dried, and chalk dust is removed from the magnetic holders with a soft brush; abrasives, solvents, acetone, alcohol and chlorine-based agents destroy the printed scale. The set operates indoors in an educational institution at +5 to +40 °C and relative humidity of 40 to 60 % without condensation. Marking and operating documentation are in Ukrainian, the service life is 5 years and the warranty period is 12 months.
