Learn Hardcore Japanese: syukudai wo wasurenai you ni, tukue no ue ni memo wo okimasu. - So that I don't forget my homework, I put a note on my desk.

V + ために
- Strong, direct purpose: “for the purpose of ~”
- Usually used when the subject can directly control achieving that goal.
- e.g. 日本語を話せるように毎日勉強します。
  vs 日本語を話せるために毎日勉強します。
  Both are possible, but ために sounds more like a clear, conscious goal.
V + ように
- Often used for:
  - Results that are not fully under your control (can, be able to, etc.)
  - Hopes, wishes, precautions, indirect goals
- In 忘れないように, it’s like “as a precaution so I won’t forget.”

In this sentence, 忘れないように、メモを置きます naturally expresses the idea of taking a precaution (putting a memo) so that forgetting will (hopefully) not happen.
You could say 忘れないために, but ように is more natural and softer/less “mechanical” here.

Why is it 忘れないように and not 忘れるように?

Because the meaning is “so that I don’t forget”, we need the negative form before ように.

忘れないように
→ “so that (I) don’t forget”
忘れるように
→ “so that (I) will forget” / “so that (someone) ends up forgetting”

So:

宿題を忘れないように、メモを置きます。
“I’ll put a memo on the desk so that I won’t forget my homework.”

If you said:

宿題を忘れるように、メモを置きます。
it would mean something like “I’ll put a memo so that I forget my homework,” which is the opposite of what you want.

Grammatically, what is 宿題を忘れないように? How does it connect to the rest of the sentence?

宿題を忘れないように is an adverbial clause expressing purpose/aim. It modifies the main action メモを置きます.

Breakdown:

宿題を忘れない – “not forget the homework”
ように – “so that / in order that”
Entire chunk: 宿題を忘れないように – “so that I don’t forget my homework”

It’s functioning like:

“In order not to forget my homework, I (will) put a memo on the desk.”

Word order in Japanese is flexible, so you can also say:

机の上にメモを置きます、宿題を忘れないように。

That version is also understandable, but putting 宿題を忘れないように at the beginning is very natural for a “reason/purpose first, action second” flow.

Why is 宿題 marked with を after 忘れない?

Because 忘れる (“to forget”) is a transitive verb in Japanese.

Someone 忘れる (forgets) something.
That “something” is marked by を, the direct object marker.

So:

宿題を忘れる – “forget homework”
名前を忘れました – “I forgot (your/my) name.”
約束を忘れないでください – “Please don’t forget the promise.”

English often says “forget about X”, but Japanese uses direct object を:

“forget about the book” → 本を忘れる
not 本について忘れる in normal usage.

What is the role of に after よう in ように?

Grammatically, よう is originally a noun meaning “way, manner, state.”

よう – “way, style, manner, state”
に – a particle that can mark a target, result, or manner

So literally, V + ように is like “in such a way that V (is true)” or “toward the state where V (is true).”

Over time, V + ように has become a fixed grammatical pattern meaning:

“so that V”
“in order that V”
“(aiming) for V to happen / not happen”

In 忘れないように:

忘れない – “not forget”
よう – “state / way”
に – “towards / into that state”

Altogether: “towards the state of ‘not forgetting’” → “so that I don’t forget.”

What does 机の上に literally mean, and how is it different from just 机に?

机の上に literally means “on top of the desk.”

Breakdown:

机 (つくえ) – desk
上 (うえ) – top, above, surface
机の上 – “the top of the desk” / “the surface of the desk”
机の上にメモを置きます – “I will put a memo on the desk.”

If you say just 机に:

机にメモを置きます is grammatically possible, but it sounds less natural and clear in this context.
〜の上に very clearly means “on top of (the surface of).”

So:

机に – often “by/at the desk” or “to the desk” (location in general)
机の上に – specifically “on the desk’s surface,” which is what you want for a memo.

Why is there a の between 机 and 上 in 机の上?

の connects two nouns, making the first one modify the second. It often corresponds to:

English “of”
possessive “’s”
or an attributive “X-” relationship

Here:

机 – desk
上 – top, surface
机の上 – “the top of the desk” / “the desk’s top” → “the desk’s surface”

This is a very common pattern:

机の下 – under the desk
机の中 – inside the desk
ベッドの下 – under the bed
山の上 – on top of the mountain

What exactly is メモ? Is it a loanword, and is it natural here?

Yes, メモ is a loanword from English “memo”, written in katakana, like most foreign-origin words.

In Japanese, メモ usually means:

“a note”
“a memo”
“a reminder written on a small piece of paper”
It can also mean the act of jotting down a note: メモを取る (“to take notes”).

In this sentence:

机の上にメモを置きます。
→ “I’ll put a memo/note on the desk.”

This is completely natural Japanese. It implies a small written reminder, which fits the idea of not forgetting homework.

(You wouldn’t normally use ノート here; ノート is more like a notebook.)

Can I say 置いておきます instead of 置きます? What is the difference?

Yes, you can say 置いておきます, and it adds a nuance.

置きます – simply “put / place (something)”
置いておきます (Vておく) – “put (something) and leave it there for later / in preparation”

So:

机の上にメモを置きます。
→ neutral: “I will put a memo on the desk.”
机の上にメモを置いておきます。
→ “I’ll put a memo on the desk and leave it there (as a preparation).”

Because the sentence is about not forgetting homework, 置いておきます is actually very natural: you’re putting the memo in advance so it will help you later.

Why isn’t the subject “I” written in the Japanese sentence?

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

In English, you must say “I”:
“I’ll put a memo on the desk so I don’t forget my homework.”
In Japanese, saying 私(は) every time sounds repetitive and sometimes unnatural, especially when you’re clearly talking about your own actions.

So instead of:

私は宿題を忘れないように、机の上にメモを置きます。

it’s more natural in many contexts to just say:

宿題を忘れないように、机の上にメモを置きます。

Listeners/readers will understand “I” from the situation.