のは～だthe one who… is; what… is
You start with what you both already know and keep the answer for the end: who, what, when, where or why. English says "the one who…", "what I…" or "it was … that".
who
The person who made this cake was my older sister.
why
I opened the window because the room was hot.
How to form it
Sentence with one piece missing + のは + that piece + です／だ
The first part is in the plain form: 作った, 探している, 悪い. A な-adjective keeps な: 好きなのは. The piece at the end stands bare, with no が or を after it.
For a reason
… のは + plain sentence + からです
What you know first, the answer last
Before のは goes something you both know or can see: someone made this cake. After it comes the news. It is は doing its usual job, with a whole sentence in front of it. の stands in for "the one", "the thing", "the time" or "the place".
Yamada drove to the station.
Says what happened.
The person who drove to the station was Yamada.
Someone drove, as you both know. The one thing that matters is who.
The second is for when one detail is the whole point: you were asked about it, you are putting it right, or you are leading up to it.
The first part shows the tense, and the end usually stays です where English has "was". Inside the first part, the one who does it takes が, not は: 私が探しているのは.
Who took this photograph?
My father did.
To ask, the question word goes at the end: だれですか, いつですか, どこですか.
When and where
I moved to this town last year.
English needs no "the time when". It just ends on "last year".
This café is where the two of them first met.
Things you'll say with it
好きなのはthe one I like is
The one I like best is autumn.
のは初めてですit is my first time
This is my first time in Japan.
Giving the reason: のは…からです
English says "I did it because…". Here what happened comes first with のは, and the reason ends in からです.
I got off the train because I started feeling sick.
Not said: 遅れたのは
(I was late because the train stopped.)
…止まったからです. Without から the two halves don't join.
Putting one detail right
The wrong detail takes ではなく, or じゃなくて in conversation, and the right one follows.
Departure is on Saturday, not Friday.
What I ordered was not tea but coffee.
Close neighbours
の・ことN5
When nothing is missing, のは only turns an action into something to talk about, like "-ing". What follows describes it.
Learning kanji is hard work.
のN5
After an adjective or a name, の is "one": the big one, Tanaka's.
There are two keys. The large one is the front-door key.
はN5
The same は after a single word: what you are talking about, then the news.
The meeting starts at three.
Check yourself
1What does this mean?
財布を
Choose an answer to see why.
2"I went home early because I had a headache."
Choose an answer to see why.
More sentences
The place where I found the key was in front of the entrance.
Mori, not I, will give the presentation.
The hardest part is the morning.