Student or Learner
"Mr. Brown is sick. Mr. Jones will be taking over the 12 o´clock class". Does take over convey that the change is temporary or permanent?
"Mr. Brown is sick, Mr. Jones is replacing him."
"Mr. Brown is sick, Mr. Jones is taking over for him permanently."
"Mr. Brown is sick, Mr. Jones is replacing him in all classes from now on."
In the second case, if the change is permanent, and Mr. Jones is replacing Mr. Brown, can I say Mr Jones is taking on the class? What other verbs can I use? Keep? Assume?
"Taking someone on" is also used in slang to mean that they are challenging someone."
"You say that you are stronger than I am, I'll take you on, on that one!"
You could use, "will teach the class(es)instead of"
"Mr. Jones will be your teacher/professor from now on"
"Mr. Jones is assuming Mr. Brown's duties/classes from now on."
I believe it depends on whether Mr.Brown is seriously ill or not. If it's
serious, then the replacement is likely to be permanent. If the opposite
is true, the replacement is temporary.