The main assumption underlying team teaching is

The main assumption behind team teaching is that the best teachers can be shared by a larger number of students.

Pooling expert teachers lets many more learners benefit from the strongest available instruction.

The idea that teachers feel bored working alone trivialises the purpose and is not the underlying assumption.

The idea that teachers are not competent contradicts team teaching, which relies on combining strong competencies.

The idea that a single teacher cannot control the class reduces it to discipline, missing its instructional aim.

Team teaching, defined by Shaplin and Olds, joins two or more teachers who share responsibility for the same students.