Ключевые слова: angle, background, beaker, biology, blackboard, blank, board, button, chalk, chalkboard, chemistry, class, classroom, clock, degree, education, experiment, flask, frame, geometry, glass, glassware, grid, hour, icon, illustration, instrument, isolated, laboratory, liquid, measure, medical, minute, object, panel, protractor, ruler, school, set, sign, symbol, test, tilt, time, transparent, watch, white,