Ключевые слова: 2, 2x26, 6, alphabet, background, black, closeup, doodle, drawing, education, element, elementary, figure, formula, graphic, learning, letter, mathematical, mathematics, number, pen, plus, ruler, school, scribble, script, section, sign, sketch, spiral, stick, student, supplies, symbol, teacher, text, university, white, writing, writingbook,