Read the text and answer to the question.

Classroom interaction is studied from a social interaction perspective to unearth the mechanisms teachers and students use to conduct their classroom business. Classroom interaction research originated, like all social interaction research, when in the 1960s recording technology such as cameras and microphones became accessible for researchers. Recording techniques have ranged from one hand-held camera to several cameras on poles, and from researchers sitting or even participating in the classroom, to those who witnessed the lesson on a monitor in an adjacent room, or only saw the recordings afterwards. Audio has been recorded following the available technology and research aims with cameramounted or separate microphones, or wireless individual microphones on the teacher or on individual students. Recent digital technology has allowed these different streams to be fed directly into a computer where they can be synchronised with each other and with subsequent transcripts. Sometimes, classroom recordings have been supplemented by interviews of different kinds, and ethnographic information on factors such as ethnicity or social class. Also, additional information has been assembled on school policy or teacher planning, and additional recordings have been in the school yard, all depending on research aims and researchers’ views on methodology and epistemology.