Many researchers say that the possibility of choosing the studying pace, the type of home assignment or the topic of an educational project makes students more engaged and willing to work, which translates into better results.
If we leave the learner some freedom of choice, they will be less competitive (or hostile towards other students) and less bored or apathetic (which happens either when the task is too difficult or when it is too easy). What is more, it will be easier for the teacher to set the threshold appropriately for a given child, and raise the bar when needed.
An open school prefers freedom of choice to obligation and appreciates the perks of making students responsible for their work. In such a school the teacher looks at what students do, supports them when they need it, guides them and encourages them to try again if they fail to succeed at a given time.