.net - Entity Framework Code First Inheritance - multiple types -

i'm using entity framework code first table-per-type inheritance. want model issue:

i've got 1 base class called: user. , 2 derived classes:

public class student : user{}
public class teacher : user {}

so want able insert user teacher , student. far know not possible in approach. how can solve in code first ? , how sample insert ?

thanks lot

you guess need create class called public class teachingstudent: user , use such cases