kodomotachi wa natsuyasumi ni umi de oyogimasu.

topic particle

Breakdown of kodomotachi wa natsuyasumi ni umi de oyogimasu.

• で: location particle
• に: time particle
• 海うみ: sea

Questions & Answers about kodomotachi wa natsuyasumi ni umi de oyogimasu.

Why is は (wa) used after 子供たち?

は marks the topic of the sentence – what the sentence is “about.”

• 子供たち = the children
• 子供たち は = As for the children… / The children…

So the sentence structure is:
(As for) the children, during summer vacation, (at) the sea, (they) swim.

In conversation, は does not mean “subject” in the strict grammatical sense; it frames the topic and contrasts it with other possible topics (e.g., “The children (as opposed to adults) swim at the sea in summer vacation.”).

Why is は pronounced “wa” here and not “ha”?

The character は is normally read “ha” in words (like はな = hana, “flower/nose”), but when used as the topic particle, it is pronounced “wa”.

So:

• As part of a word: は → ha
• As topic particle: は → wa

This is just an irregularity of Japanese writing vs. pronunciation that learners have to memorize.

What does the たち in 子供たち mean?