Go to 
Reporting > Reports > Conduct (tab) > Detentions by Student
This tabular report enables you to view a list of students that have been given a detention this academic year. It gives the pupil's name, form, the number of detentions assigned and it gives you the option to view more details.
Please note that your reports may display different names if your school has customised conduct types in Admin > Config > Custom Relabelling.
You are able to report on current, former and future students.
If you click onto the child's surname the link will take you directly to that child's Conduct page in their personal profile.
Going back to the report, clicking on More Details you will get additional information on the detention.
To print off either table, click on the Word, PDF or Excel icon on the top right of the screen.