I found this interesting…
Polk (Montessori Today) states- “Montessori discovered that once
children become self-directed they do their best work when allowed a
three-hour uninterrupted work cycle. Therefore, the elementary class
period lasts for three hours in the morning and three more in the
afternoon without ceasing for recess, gym, foreign language, art,
music, or other events.”
She gives as an example from Maria Montessori, p. 36-From Childhood to Adolescence
“The best they [educators-other than Montessori] could do was to
compromise by reducing hours in instruction to the minimum, coming
out from the curriculum grammar, geometry, and algebra, making
outside play obligatory and postponing the age for entry into
school. But however, much free periods have been increased and
children are urged to play rather than study, strangely the children
have remained mentally fatigued notwithstanding all these reforms.
Montessori schools have proved that children need a cycle of work for
which they have been mentally prepared: such intelligent work with
interest is not fatiguing and they should not be arbitrarily cut off
from it by a call to play. Interest is not immediately born, and if
when it has been created, the work is withdrawn, it is like depriving
a whetted appetite of the food that will satisfy it.”
This is much like an engaged preschool aged child repeating an
activity over and over. Montessori seems to conclude that it is best
not to interrupt the flow of learning for any child.
I still hate to stop working on something until I have reached a
certain stopping point. If I have to pick up the activity again, it
takes me twice as long to finish.
Here are some more links about the 3 hour work cycle.