tizu de kyori wo kakuninsita.

Here, で marks the means/tool used to do something.

So 地図で means:

• using a map
• by means of a map

In this sentence, the speaker checked the distance with a map.

This is a very common use of で:

• 電車で行く = go by train
• 箸で食べる = eat with chopsticks
• スマホで調べる = look it up on/with a smartphone

So 地図で距離を確認した is literally something like:

• checked the distance using a map

を marks the direct object of the verb.

The verb here is 確認した (confirmed / checked), and the thing being checked is 距離 (distance).

So:

• 距離を確認した = checked the distance

This is the normal pattern:

• 何を確認する = confirm/check what?

Examples:

• 予定を確認した = checked the schedule
• 時間を確認した = checked the time
• 住所を確認した = checked the address

確認した is the past plain form of 確認する.

• 確認する = to confirm, check, verify
• 確認した = confirmed, checked, verified

In many everyday contexts, 確認する is a little more like check/verify carefully than just casually look at something.

So compared with other verbs:

• 見た = saw/looked at
• 調べた = investigated/looked up
• 確認した = checked/confirmed to make sure

In this sentence, it suggests the speaker checked the distance to make sure it was correct or to verify it.

Japanese sentences normally put the main verb at the end.

So the basic structure is often:

• topic/subject
• time/place/method/object
• verb

Here:

• 地図で = using a map
• 距離を = the distance
• 確認した = checked

That final verb position is one of the biggest differences from English.

Yes, to some extent. Japanese word order is more flexible than English because particles show each word’s role.

For example, these are both natural:

• 地図で距離を確認した。
• 距離を地図で確認した。

Both mean basically the same thing:

• checked the distance using a map

The nuance can shift slightly depending on what comes first, but the core meaning stays the same because:

• で shows the method
• を shows the object

However, the verb usually still stays at the end.

Japanese often omits the subject when it is clear from context.

So 地図で距離を確認した。 could mean:

• I checked the distance using a map
• He checked the distance using a map
• She checked the distance using a map
• We checked the distance using a map

Japanese frequently leaves out words like I, you, or they if the listener can figure them out from the situation.

That is very normal and natural.

In this sentence, the most natural interpretation is using a map.

That is because で often marks the tool or means.

If you specifically want to say something exists on the map, Japanese often uses other wording, depending on the verb. For example:

• 地図に載っている = is shown on the map
• 地図の上で = on top of the map (physically on it)
• 地図上で = on the map / in map terms

So in 地図で距離を確認した, で is best understood as:

• with a map
• by looking at a map

Not in this sentence.

で is correct because the map is the means/tool used to check the distance.

If you used に, it would suggest a different relationship, such as:

• location
• target
• result of placement

For example:

• 地図に印をつけた = put a mark on the map
• 地図に道が書いてある = a road is written on the map

But for using a map to do something, で is the natural choice:

• 地図で調べる
• 地図で確認する

The readings are:

• 地図 → ちず
• 距離 → きょり
• 確認した → かくにんした

So the full sentence is read:

• ちずで きょりを かくにんした。

That is because 確認する is a suru-verb.

Many Japanese nouns can combine with する to make a verb:

• 勉強する = to study
• 電話する = to call
• 確認する = to confirm/check

To make the past tense, する changes to した:

• 確認する → 確認した

So:

• 確認 is the verbal noun
• する turns it into a verb
• した is the past form

This sentence is in the plain past form, so it is not polite in the formal -ます style.

• 確認した。 = plain past
• 確認しました。 = polite past

That does not necessarily mean it is rude. Plain form is used all the time in:

• casual conversation
• diaries
• narration
• written summaries
• talking to friends/family

If you wanted to make this sentence polite, you would say:

• 地図で距離を確認しました。

They are similar, but the nuance is a little different.

• 距離を確認した = checked/confirmed the distance
• 距離を調べた = looked up/investigated the distance

確認した focuses more on making sure or verifying. 調べた focuses more on finding out information.

So if the distance was already something relevant and the speaker wanted to make sure of it, 確認した fits well.

If the speaker was actively researching the distance for the first time, 調べた could also work.

Yes. The spaces are just there to help learners see the parts clearly.

Normally, Japanese is written without spaces:

• 地図で距離を確認した。

Texts for beginners sometimes add spaces to show:

• word boundaries
• particles
• sentence structure

But in natural Japanese writing, you would usually not include them.