On Sunday I taught a child at work the difference between red and blue tap.
As I went to the toilets in the restaurant, I spotted a little girlie standing behind the door next to a sink. The water was running and she was standing there with wet hands in the air and a few tears were rolling down her cheeks. At first I though: This kid is wasting water! So I went to turn it off and meanwhile asked her what is wrong.
"The water is hurting mee-e-ee!" she sobbed. The poor kid turned the tap on, but managed to move it all the way to the left and then tried to wash her hands in the steamy hot water and when she couldn't, she just stood there and cried and suffered quietly while her teacher waited for her outside the toilets.
So I explained the difference between red and blue and what they mean, we turned the tap to the right, colled the burnt hands down in cold water and washed the hands properly. Then explained it all to the teacher, who wiped the tears away and explained: "Oh Honey, why didn't you tell me? You have to let me know when something like that happens. Sometimes it's OK to scream, you know?"
Yes, sometimes it is even necessary. Unless you want to suppress your pain and boil your hands.