Passt; ich würde allerdings ein Komma nach "well" setzen, aber das ist Ansichtssache.

Or a semicolon after "often", depending on what you want to say ;-)

(I guess you want to say the version with the comma!)

after "often"? Please explain that structure.

Without the comma, you could (if the fancy took you) read it as saying that the children can't speak German well and often.

Disagree with #1! -- not the comma (it correctly belongs "well"), but with das ist Ansichtssache.

"Often, the teachers can't either." is a complete, independent clause. Thus, when it joined to the first independent clause with a coordinating conjunction, it must have a comma (before "and").

Note: Some people consider the comma I inserted after "often" to be optional. I don't, but even Chicago Manual of Style would allow for its absence.

#0:
Statt 'pupils' evtl. 'students'?

Wie ist das eigentlich mit dem 'pupil'?
Ist das aus der Mode gekommen? eine AE/BE Geschichte? nur noch ein spezieller Anwendungsfall (junge Schüler?) ?

You only use "pupil" when you are talking about the pupils at a specific school. You can't use it as a description of someone's general status, e.g. this is not correct: *"Mary is a student but her brother is still a pupil".

In this case "pupil" is contrasted with "teachers" and does sound like it means the ones at a specific school, so I'd be OK with it. It is more of a formal use, though -- used more by teachers, for example.

Danke!

Ich bin zufrieden, wenn das "can't either" stimmt.
In der Klassenarbeit, die ich gerade korrigiere, hieß es nämlich ... and often the teachers too. Dass das falsch ist, war mir klar, nur bei der Korrektur war ich mir unsicher. Aber das liegt vor allem am "often", was ja auch in der Komma-Diskussion problematisiert wird.

Wie wäre denn:
The pupils can't speak German well, and the teachers often can't either. ???