They also have trouble with visual and linguistic symbolism, even with such simple concepts as same versus different and more versus less. (scientificamerican.com)
It seemed like such a simple concept to me — it feels better to not be covered in urine than to be covered in urine. (kidskillcoolness.com)
The game is more fun than it has any right to be, because it's just such a simple concept executed in a very good way. (thesixthaxis.com)