Episode 43 of "Malcolm in the Middle"
s03e02 Emancipation (2/2)

Still reeling over Francis' break for freedom, Lois and Hal find themselves face to face with their newly independent son. While at home, Francis wins back Hal's support, but Lois is a completely different story. Also, Malcolm and the Krelboynes meet their match when a new teacher—a former Krelboyne himself—is assigned to the class. He sets up a ranking system that pits the students against each other and eventually drives them to the brink of insanity.