Many children break their arm, particularly just above the elbow. It’s a common break because it can easily happen when you put your hand out to stop a fall, something that kids do a lot.
When a bone breaks, it could break but still stay aligned or it can break and move out of position. If the bone stays aligned, it is possible that it doesn’t hurt as much as it might if it has moved, if the child isn’t forced to move the arm. Therefore, by babying the arm, but not using it, it is possible to go on without anyone realizing that the bone has actually broken.