～ついでに

When to use

"While I'm at it" - doing something extra alongside the main action, not purely a topic shift.

Explanation

The ～ついでに grammar point is used to express doing something 'on the occasion of' another action. It can mean 'while you're at it', 'by the way', or 'in passing'.

• 買かい物ものに行いくついでに、郵便局ゆうびんきょくで手紙てがみを出だしましょう。

  Let's drop off a letter at the post office while going shopping.

  Kaimono ni iku tsuide ni, yuubinkyoku de tegami wo dashimashou.

• 図書館としょかんで本ほんを借かりたついでに、友達ともだちに会あいました。

  I met my friend while borrowing a book from the library.

  Toshokan de hon wo karita tsuide ni, tomodachi ni aimashita.

• 日本にほんに来きたついでに、有名ゆうめいな観光地かんこうちを訪おとずれたいです。

  While visiting Japan, I'd like to see some famous tourist spots.

  Nihon ni kita tsuide ni, yuumei na kankouchi wo otozuretai desu.

• 映画館えいがかんに行いったついでに、新作しんさくのポスターを見みました。

  While going to the movie theater, I saw a poster for a new film.

  Eigakan ni itta tsuide ni, shinsaku no posutaa wo mimashita.

Topic Shift (By The Way)

• A。そういえば B。~souiebaN2Recalling something related to A; 'speaking of which', 'by…
• ところでtokorodeN3Used for changing the topic or bringing up a new topic…
• A それはそうと B。A Sore wa sou to BN2Changing the topic; 'by the way', 'speaking of which'.
• A。ちなみに B。A. Chinamini B.N2Used to give additional information about the topic; 'by…
• A。さて B。A. Sate B.N2Indicates a sudden change or shift in the topic or…

Compare when to use each