Mr Church is concerned his relationship with Miss Postern has taken a downward turn after a misunderstanding over a date.
When she sets up a careers workshop and the guest speaker is an old friend of hers, who happens to now be a best-selling children's author, Miss Postern starts to question her own career path. Will Mr Church lose his girl?
Meanwhile, Mr Gunn is now teaching geography as well as PE. Seeing as he can't even pronounce the subject name, it looks like this has disaster written all over it! Things are looking up for Mr Martin though, as he's set to launch a successful pop career – or is he?
Big School, BBC1, 9.30pm
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