kodomo ha asa hayaku okiruno wo iyagarukoto ga arimasu.

は marks 子供 as the topic of the sentence.

Here, 子供は gives a general topic like as for children or children, in general. That fits well because the sentence is talking about a tendency or something that happens sometimes.

If you used 子供が, it would sound more like you are specifically identifying the one who does this, rather than setting up a general topic.

So:

• 子供は = as for children / children generally
• 子供が = children are the ones who... or a more specific subject focus

Also, 子供 can mean a child or children, depending on context.

早い is an i-adjective, and 早く is its adverb form.

Because it modifies the verb 起きる (to get up / wake up), you need the adverb form:

• 早い = early
• 早く起きる = to get up early

So:

• 朝 = morning
• 朝早く = early in the morning

This whole part describes when the waking up happens.

The の turns the verb phrase into something noun-like. This is often called nominalization.

• 起きる = to get up
• 起きるの = getting up / the act of getting up

In this sentence, the speaker needs to treat getting up early in the morning as a thing that can be disliked. So the action is turned into a noun phrase:

• 朝早く起きるの = getting up early in the morning

Because 起きるの is the object of 嫌がる.

Structure:

• 朝早く起きるの = getting up early in the morning
• を嫌がる = to dislike / resist / act like one dislikes it

So:

• 朝早く起きるのを嫌がる = to dislike or resist getting up early in the morning

Even though 起きるの comes from a verb, once it is nominalized with の, it can take を like a noun phrase.

嫌がる means something like:

• to show dislike
• to act as if one dislikes something
• to be reluctant to do something
• to resist something

This verb is often used when talking about someone else's visible reaction, especially children.

Compare:

• 嫌いだ = to dislike; a state or preference
• 嫌だ = unpleasant / I don't want to / I hate it
• 嫌がる = to show dislike, to act reluctant, to resist

So in this sentence, 嫌がる suggests that the child or children show reluctance about getting up early, not just that they have an abstract opinion about it.

Because 嫌う and 嫌がる are not the same.

• 嫌う means to dislike in a more direct, lexical sense.
• 嫌がる focuses on displayed reluctance or resistance.

With children, 嫌がる is very natural because it often refers to behavior you can observe:

• not wanting to do it
• complaining
• resisting
• making a fuss

So 朝早く起きるのを嫌がる sounds natural in the sense of they don't want to get up early and show that reluctance.

Yes, both can nominalize, but they are doing different jobs here.

1. の in 起きるの turns to get up early into a noun phrase:

   • getting up early

2. こと in 嫌がることがある is part of the pattern 〜ことがある, which means:

   • there are times when...
   • sometimes...

So the sentence structure is roughly:

• [getting up early] を嫌がる
• such occasions exist
• therefore: sometimes they dislike/resist getting up early

In other words:

• first nominalization: the action being disliked
• second nominalization: the whole event, inside the pattern 〜ことがある

Here, 〜ことがあります means sometimes or there are times when...

So:

• 嫌がることがあります = there are times when they resist / sometimes they resist

This pattern is very common in Japanese for describing occasional events or tendencies.

A key point: this is not the same as the pattern meaning have experience doing something, which uses a past plain form before ことがある.

Compare:

• 行くことがある = sometimes go
• 行ったことがある = have been / have the experience of going

In your sentence, it is the dictionary form 嫌がる, so the meaning is sometimes do.

Because when a verb comes before の to modify or nominalize a clause, Japanese normally uses the plain form, not the ます-form.

So:

• 起きるの = getting up
• not 起きますの in this structure

This is very common in embedded clauses:

• 食べること
• 行くの
• 勉強する人
• 寝る前

Even in a polite sentence ending with あります, the clause before の still stays in plain form.

Yes, 起きることを嫌がる is possible, but 起きるのを嫌がる often sounds more direct and natural for a concrete action.

Very roughly:

• の often feels more immediate, concrete, or close to an actual action/event
• こと often feels more abstract, general, or formal

Since this sentence already ends with ことがあります, using 起きることを嫌がることがあります would also sound a bit repetitive.

So 起きるのを嫌がることがあります is a natural choice.

It can be either. Japanese nouns usually do not mark singular vs. plural the way English does.

So 子供 may mean:

• a child
• children

In this sentence, because the topic is general and the sentence describes a tendency, many learners would naturally understand it as children in general. But context could also make it refer to a particular child.

If you wanted to make plurality clearer, Japanese might use:

• 子供たち = children

But very often that is unnecessary.

The one doing the disliking is 子供.

The sentence topic is 子供は, and the predicate describes what children sometimes do:

• 朝早く起きるのを嫌がることがあります
• sometimes they resist getting up early in the morning

So the sentence is about the children's behavior, not the speaker's feelings.

Also, 嫌がる is especially natural because it is often used for another person's observable reaction, not the speaker's own inner feeling.