I may come across as harsh, but why wouldn't a child doing 4th grade math (accelerated from 3rd) know their times tables. (Know, not memorize.) It's just such a teensy weensy easy peasy thing to do. I don't think it's unreasonable for a school to question the mathematical ability of a child who doesn't do this. The child may in fact be highly able mathematically, but they need to show their ability.