First of all, there is no magic in the number “3”.  The three-hour work cycle idea was begun as a way to focus on the fact that the children need long periods of a work cycle without adult-engineered activities.  Without the possibility of time for deep-engagement, we do not see deep-engagement. 

What has evolved in some situations with trying to adhere to this idea – a 3-hour uninterrupted work cycle – has evolved to busy work, rather than following the children’s rhythms.  On any day, this idea of a 3-hour work cycle does NOT mean that a small group (3 or 4 children) cannot be gathered for a brief lesson (vocabulary enrichment, grace and courtesy, etc.) and then returning to work.

Some days the work cycle may go for 2:45 minutes, breaking down and then another long work session in the afternoon.  Some days the morning work cycle will extend beyond 3 hours.  The important thing is to never interrupt children to gather them, asking them to put their work away.  

Towards the end of a work cycle, some children may be ready to gather while others are still deeply engaged in their work.  This naturally evolves as the children move towards a more “normalized state” (as Montessori called it).

We must always remember our goal:  children are supported in reaching a state of peaceful, calm, satisfying activity in which they are completely engaged.  Montessori referred to this as a process of “normalization”; call the state what you would prefer but be clear that this is the goal.  Montessori states in The Absorbent Mind, chapter XIX, “…It [normalization] is the most important single result of our whole work.”

In the Absorbent Mind, Chapter XXVI, “Discipline and the Teacher”, in the sub-section, “The child in Chaos”, re-read (3) which talks about imitation where Montessori intimates that children need to be able to choose work based on their interest and to become deeply engaged in this work.  This is what leads to concentration which will lead them away from disruptive behaviour.