Learn Hardcore Japanese: kodomo ha gakkou ni ikimasu.

は is the topic marker. It tells the listener that 子供 is what we’re talking about—in English you might think of it as “as for the child(ren)….” It does not necessarily mark the grammatical subject (though topics are often subjects), and it can also imply contrast with other possible topics.

Why is は used instead of が?

が introduces new information or emphasizes the subject.
は marks known information or the general topic.
Here, we’re making a general statement about children going to school, so は is appropriate. If you wanted to single out “the child” against others (“It’s the child who goes to school”), you could use が.

What function does に serve in this sentence?

With movement verbs like 行く (“go”), に marks the destination. So 学校に行きます literally means “go to school.”

Could we use へ instead of に?

Yes. 学校へ行きます also means “go to school.”

へ emphasizes the direction or path.
に emphasizes arrival or the goal.
In everyday speech they’re mostly interchangeable in this context.

Why is 行きます used instead of 行く?

行きます is the polite (–masu) form in non-past tense, suitable for formal or everyday polite conversation. 行く is the plain (dictionary) form and is used in casual speech or writing.

Does 子供 refer to one child or multiple children?

Japanese nouns are usually unmarked for number. 子供 can mean “child” or “children” depending on context. If you need to stress “children” you can say 子供たち, but it’s not always required.

Why does the verb come at the end of the sentence?

Japanese follows a Subject-Object-Verb (SOV) order. Even though は marks the topic, the verb 行きます naturally appears at the end in Japanese syntax.

Can you drop 子供は and just say 学校に行きます?

Yes. Japanese often omits topics or subjects when they’re understood from context. 学校に行きます alone can mean “[I/you/she/they] go to school,” depending on who the topic is in the conversation.

Is 行きます present or future tense? Does it mean “go” or “will go”?

The non-past form 行きます can express both habitual action (“go regularly”) and a future event (“will go”). Without a time adverb, it’s ambiguous; context tells you which.

Why isn’t 学校 marked with を like a direct object?

行く is an intransitive verb of movement, so it doesn’t take a direct object. Instead, you mark the place you move to with に (or へ). You only use を when a verb acts directly on something or when expressing movement through a place (e.g., 道を歩く, “walk along the road”).