Why was Auggie homeschooled?

Auggie's mother homeschooled him because he'd had twenty-seven surgeries since his birth, and as a result he was often sick.

People think I haven't gone to school because of the way I look, but it's not that. It's because of all the surgeries I've had. Twenty-seven since I was born.

I used to get sick a lot. That's why my parents decided it was better if I didn't go to school.