I dont believe that to be true. I have beta Thalassemia major. from my guess my condition is much worse than yours or of your children. hb 5.5 ~ 6
When i was a child the hb levels where not much of a problem. The tiredness only affected after i reached 18. The hb is just not enough to cope with the age. I had to take regular absence for my transfusions but that was it. And as far as learning is concerned, you made me laugh. I have seen parents who treat their children too differently and let them exploit this point of view (children are smart, dont under estimate them
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Studying is not like a lot of physical work, and studying for long hours does not do any good anyway. so i see no reason for them to fail. They can study just as well as any other child. They just need determination and some support. Dont just force them to homeschooling, let them try out regular schools too. Its not just the books and lessons that you learn from schools. They need to believe in themselves.
My parents sent me to a small school very near to my house, so even walking there everyday was not much of a hard physical work. Even though they never pushed me much in terms of studying, they always had their eyes on my study and grades. Which was just enough. My point is give freedom to a child when he/she is ready for it. Dont let them neglect studying before they even realize what they are doing.
By the way now I am 26 I have a BSc Engineering degree in Computer Engineering. I was never the top of the class for sure. But i always was above average and never felt any disability in learning.