Action research is a development tool for a teacher that involves observing or gathering other data about a class through interviews, case studies, and questionnaires. A teacher can establish a cycle of identifying problems, planning changes in response, implementing changes and gathering and analysing data to evaluate the implementation. Action research can be used to help general development or to resolve specific problems with teaching or learners.

Example
A teacher has problems with giving feedback to learners on speaking problems and decides to record their classes. They then analyse the recordings to identify more effective ways of correction. They implement changes based on this, and collect data to analyse whether feedback is now more useful to learners.

In the classroom
Peer observations, learner and teacher diaries, audio and video recordings, case studies, questionnaires and interviews with learners are all methods that can be used to gather data for action research.

Further links:

https://www.teachingenglish.org.uk/article/action-research

https://www.teachingenglish.org.uk/article/action-research-easy-1-2-3

https://www.teachingenglish.org.uk/article/action-research-panel-discussion

https://www.teachingenglish.org.uk/article/a-handbook-exploratory-action-research

https://www.teachingenglish.org.uk/article/action-research-stop-start-continue