Still a Lingering Question??

I'm still struggling with what to do with the kids who can go right to a correct number sentence but can't create a 'thumbnail sketch' to prove it would work?....I'm hoping that by having them articulate where the numbers came from and then modeling what that might look like in a 'sketch' will help them to realize that it doesn't have to be this great picture but just something that would work to help them explain to others where the numbers came from.