Go to Students > Demographics > Derived Indicators. Select Age.
Click into the filters to select an age or filter by student group.
You can also choose to chow the inverse of the demographic - in this example it would show you everyone who is not 10.
You can see a list of students, including their name, year groups, registration form and the dates the start and stop being this demographic.
You can download the table, or click on a student to see more details, or jump to their profile.