PowerSchool is a huge student information system which is used worldwide in International Schools. It's not open-source but It provides us a lot of features. One of them is pages customization.
+ In a custom page, you can make a SQL query to get the data. For example: to get all the teachers (staffstatus=1) of Elementary School (schoolid=3) which are still active (status=1), and order the result by last name:
SELECT DISTINCT t.Last_Name, t.First_Name
FROM Users t, SchoolStaff ss
ORDER BY lower(t.Last_Name)
PowerSchool's official website: http://www.pearsonschoolsystems.com/products/powerschool/