The two other sons – Sh’mini
These sons, according to Rav Naftali Zvi Berlin, were told the statement of the Talmud (B’rachot 63b) that whoever takes in silence his teacher’s anger deserves to become a teacher of halachah.
The Torah says that when God punished Nadav and Avihu, Aaron had been silent (Lev. 10:1-3). Elazar and Itamar were not unaffected by what had befallen their brothers and they actually made a mistake in their halachic reasoning on an aspect of the laws of the sacrifices (Lev. 10: 12-20). Aaron understood their feelings and explained the situation to Moses. So Elazar and Itamar had a lesson in how to react to a situation.
From Aaron they should have learnt silence in the face of tragedy. Eventually they did learn their lesson and we admire them for it, but we admire Aaron even more for the example he set his sons.