Complex sentence: Tartakovsky first pitched the series to Hanna-Barbera's animated shorts showcase "World Premiere Toons", basing it on student films he produced while attending the California Institute of the Arts.
Split into simpler sentences: Tartakovsky first pitched the series to Hanna-Barbera's animated shorts showcase "World Premiere Toons". He based the series on student films he produced while attending the California Institute of the Arts.