Access - they would need to get parental consent to be able to carry out their research as well as gatekeepers like headteachers might stop them as well because headteachers might limit the researchers' accesses to portray a certain image. The researcher would have to consider this while researching their topic as it might cause the school to be shown in a bad light, causing them to have limited access.
Relationships - the researcher may be in disguise as a teaching assistant, which may cause the pupils to be less likely to trust the researcher and give an honest response. However, they may try to develop a rapport with them first to establish trust, But for pupils who are more impressionable and likely to disclose information to the researcher.
Time - when does the researcher have access to the pupils and how will the school handle time being taken out of the student learning time, if the method is out of school, how long will it take to get all the information to complete the research.
Sample Size - when a pupil is not in school or is excluded how will the researcher be able to collect enough information to be able to make the finding generalisable or could the sample be biased due to having a large number of responses from one specific group and not a lot from any of the others