Left handed children, how can you tell, other then favouring the left hand to the right?
As someone who works with children I can tell you that more left handed writers will write certain letters backwards or upside down but not all. Special attention needs to be given to the act of writing as a skill with lots of opportunities to investigate what feels comfortable to the child. By the time a child is ready for middle school or high school, writing backwards or upside down should have rectified itself. The only exceptions here will be children who have special education needs, in particular those with dyslexia who will forever write with a struggle. You should take into consideration that in many instances how a child performs in school might not necessarily be an indicator as to what level of success they will have in the real world. Alan Sugar and Richard Branson were both diagnosed with dyslexia, yet they are also highly successful in life.