Ключевые слова: activity, answer, brain, challenge, check, child, children, crossword, disease, easy, education, educational, elderly, entertainment, exercise, fun, game, hobby, kid, learn, learning, leisure, logic, logical, mind, number, old, paper, pastime, patient, play, practice, preschool, puzzle, quiz, rebus, relax, riddle, school, senior, sheet, skill, solution, solve, solving, square, test, think, training, worksheet,