To run this go to Reporting > Reports > Students (tab) > Special Cohorts.
In this report enter the Date Range you wish to look at mobility for and select a Filter to run the report. For example Whole School if you want to see mobility at a whole school level or year if you want it broken down by year. Then click Choose to run the report.
You'll then see the mobility in and mobility out columns:
To view this information in more detail you can use the admissions and leavers report - Reporting > Reports > Students (tab) > Admissions & Leavers.
On this report select the date range you wish to look at and either departures, arrivals or both and this will produce a list of all students who have left and arrived during this period. Please be advised if departures is selected ensure to select to include former students as well as current students.