Ethan Foley is a student at "the Enriched Learning Center for Gifted Children" where he was seen first time. Ethan is also barely whized at episode "Homer's Odyssey" when he is at school trip going to visit a Springfield Nuclear Power Plant with his class. His appearance seems to resemble Milhouse's Friend.
Episode Appearances
Episode – "Bart the Genius" 
Episode – "Homer's Odyssey"