Montessori realised that if children spent too long a time on a complex task or failed to master the necessary details, the exercise would cease to interest them. Therefore she suggested that points of interest be interspersed throughout each activity. These points guide the child toward his or her goal and stimulate repetition and interest by offering immediate feedback, or what Montessori called control of error. The child's performance becomes refined through trial and error, the points of interest acting as signposts along the path to success.