I'm nearly done teaching my son to ride his bike without training wheels.  He yelled a few times, but I didn't.  I remembered from teaching his sister what it felt like to be standing next to the bike while they try to figure out how to rid, so I knew what to expect, nothing surprised me, I didn't get upset.
But his poor sister.  She still remembers how I had a panic attack when she accidently rolled into street and a car was sort of nearby but not a real threat. This was when she was learning to ride with training wheels. We had her set up on the driveway pointed to the street, and she just boldly pushed away and rolled as far as she could go. She thought she did great! Why was daddy yelling at her for it?
The boy, we never ever let him even approach his bike while it was pointed towards the street.  He's going to have so many fewer negative memories of his parents than our daughter will.

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