Ключевые слова: abstract, algebra, background, biology, black, blackboard, board, calculate, calculation, chalk, chalkboard, chemistry, complex, complicated, doodle, drawing, drawn, education, equation, formula, graphic, hand, handwriting, handwritten, icon, integral, lab, math, mathematics, pattern, physics, plot, print, research, school, science, scientific, seamless, sheet, sign, sketch, smart, student, teacher, technology, texture, theory, university, writing,