The teacher says we are her children, and I call her sister. What the hell was she thinking? The teacher is not stupid?
I think what the teacher wants to express is that she loves teaching. I hope you can study hard and see that you can achieve something, just like seeing your children grow up healthily day by day, and feel sincerely happy about it. I hope you will study hard, live up to your teacher's hope and become a useful talent for the future human progress and development.