How to change the value of every column

Question

For example i wanna change the value of measurement_done column for every user

below is an example data how do i do so?

Example code for how I update the value of a specific user

I wanna know how to update every users value

 Students students = new Students(snapshot.child("userName").getValue(String.class), snapshot.child("password").getValue(String.class)
        , snapshot.child("section").getValue(String.class)
        , snapshot.child("teacherName").getValue(String.class)
        , snapshot.child("email").getValue(String.class)
        , "no","yes"
        ,snapshot.child("subtraction_done").getValue(String.class)
        ,snapshot.child("division_done").getValue(String.class)
        ,snapshot.child("multiplication_done").getValue(String.class)
        ,snapshot.child("measurement_done").getValue(String.class));

dbRef.setValue(students);