To be honest, in my classroom I allow students to frequently move around as long as they are doing well in the class. My classroom is rather large, and I have both tables and desks. I assign students to desks, but if a student wants to sit at a table or on the stool I allow them to do so until it gets in the way with their instruction. In your situation, I would try to use positive reinforcement to coax the student from their cubby. I would make it something unique for them so that it really piques their interest. However, this would be strictly to help the student develop emotionally and socially. If the student is doing well regardless of where they are, and they can see what you are trying to teach I may would allow them to remain there.

Maybe you could allow certain activities to be completed around the room. For instance, during independent reading the students may pick where they go to read as long as they are on task. If that student wants to go to their cubby, they are allowed. You could also have that student be a 'cubby monitor.' If they complete an assignment at their seat, they may then go and check the cubbies, making sure all of the students have their things in order. Sometimes implementing a job can help.

The teacher should talk to the parents to see if there are any underlying issues that can be addressed. If the student is completing their work, I would allow them to work there short-term, but eventually the student needs to be comfortable at the desk without throwing a tantrum. The teacher could try to get the student to explain what they like about the cubby and maybe elements of the cubby could move to their desk area. Maybe the student could personalize their desk to be more comfortable. The emotions and feelings of students shouldn't be disregarded. They are usually behaving in a certain way for a good reason and need help to form healthier behaviors.

What you could do is have work time in the classroom more "free" if you will. This way, there is a purpose for letting them do their own thing while completing work. When it comes down to it, whether they're doing their work at their desk or in a cubby, they're doing their work! That's so important. Tell them they can stay there if they do their work.

I would try to understand the issue and also incorporate it into his instruction somehow. I would not make a huge discipline deal out of the cubbies because this will likely create an even bigger problem. We can not always go to disciplining over an unwanted behavior. We need to sit back and look at the big picture, there is a reason why he behaves this way, we just need to figure out why.

It may be possible that there is something in the cubby that the student is attached to. I am picturing a low income student with few possessions. Maybe this student could keep their personal items with them. If the class has tables, maybe give this student their own desk with space to keep personal belongings close. If there is one item that can be identified, maybe allow the student to keep that item with him or her.

I would have to suggest an activity that requires the student to move around. This could include a scavenger hunt or possibly working with another student at their desk.