..which is a good start but I have no idea how to turn an assignment that says something like "what number comes after 10?" into something challenging for him.
Humor Alert, but
How about - in base 6, what number comes after 10?
To three decimal places, what number comes after 10?
What is the lower prime number, greater than 10?
What is the lowest square which is greater than 10?
Skip counting by 2's, what number comes after 10? By 5's? By 7's?
Of all the fractions you know, what number is near, but greater than, 10
Sorry, couldn't resist. It's my special gift. But really, this is why we have curriculum writers and specialist, yes?
I hope they give up on him doing the regular Math soon, and allow him to 'place out'
Grinity