[Regarding] a rova and a half-rova, [if] the rova becomes tamei, the half-rova does not become tamei. [If] the half-rova becomes tamei, the rova does not become tamei. They said before R’ Akiva: Given that the half- rova is the exterior of the rova, a utensil whose interior became tamei, does not its exterior become tamei? He said to them: [This question] is that of the group [of students who sit] in front, or perhaps the rova is [considered] the exterior of the half-rova! [Thus,] a utensil whose exterior becomes tamei, its interior does not become tamei.