How did my mom know to ask mexto pull the fire alarm when a student in her class fainted?

When a student in my mom"s class my mom told me to pull the fire alarm as 911 was not working for some reason. The student was not conscious. How is it that my mom asked me to pull the fire alarm ad opposed to another student. My mon watched me and said to kick the glass and pull the handle. How did my mom know the alarm had glass if she was on the other side of the room and to pull the handle The fire department said we dud the right thing ad 911 was not going through on the cell or landline. Would u do the same thing if 911 was not working.