Powney and Watts (1987): children have different logic and are more literal minded so they may focus on more unexpected questions - meaning more training neccasary. Higher costs.
Bentley (1987): showed 'jokey' image of her with her daughter to reduce formality in a structured interview.
Bell (1981): pupils may see interviewers as 'teachers in disguise' - especially on school grounds
Greene and Hogan (2005):
open-ended questions
no interrupting
tolerate long pauses
recognise children are more suggestable
avoid repeating questions
Greene and Hogan (2005): group interviews especially useful for pupils as it reproduces the classroom environment