When I was a child, I was a "genius"—the kind you sometimes see profiled on the local news. I started reading at 2. I could multiply two-digit numbers in my head when I was 5. One of my earliest memories is working out a way to generate Pythagorean triples. In third grade, I commuted to the local junior high to take geometry. Kids on the playground would sometimes test me by asking what a million times a million was—and were delighted when I knew the answer.

Many advocates for gifted education are similarly delighted...