Complex sentence: His maternal uncle, Henry Aron, oversaw his education, first at the Lycée Condorcet and then at the École Normale Supérieure where Hauser came first in both the entrance and leaving examinations.
Split into simpler sentences: His maternal uncle, Henry Aron, oversaw his education at the Lycée Condorcet. Hauser then went to the École Normale Supérieure where he came first in both the entrance and leaving examinations.