zyugyou no aida ha, sumaho wo tukaimasen.

Here, の links the noun 授業 (class, lesson) to あいだ (during, while, interval).

So:

• 授業 = class
• あいだ = during / while
• 授業のあいだ = during class

You can think of の here as something like of or as a noun-connector:

• 授業のあいだ = the period of class / during class

This is a very common pattern:

• 夏休みのあいだ = during summer vacation
• 会議のあいだ = during the meeting

The は marks 授業のあいだ as the topic or setting being talked about.

So the sentence structure is roughly:

• 授業のあいだは = as for during class / during class,
• スマホを使いません = I don’t use my smartphone

This は often gives a sense of contrast too, even if it is mild. It can imply something like:

• During class, I don’t use my phone.
• (Maybe at other times, I do.)

Japanese often uses は after time expressions or situations when setting the context:

• 朝は コーヒーを飲みます。 = In the morning, I drink coffee.
• 仕事中は 話しません。 = While working, I don’t talk.

を marks the direct object of the verb.

The verb here is 使います = to use.
What is being used? スマホ.

So:

• スマホを使います = use a smartphone
• スマホを使いません = do not use a smartphone

This is one of the most basic particle patterns in Japanese:

• 本を読む = read a book
• 水を飲む = drink water
• スマホを使う = use a smartphone

使いません is the polite negative non-past form of 使う (to use).

Breakdown:

• dictionary form: 使う
• polite form: 使います
• polite negative: 使いません

The non-past form in Japanese can refer to:

• a general habit
• a rule
• a future action

So 使いません could mean:

• I do not use it
• I won’t use it
• I don’t use it during class

In this sentence, it most naturally sounds like a general rule or habit: I don’t use my smartphone during class.

Grammatically, it means I don’t use my smartphone during class.

Japanese often leaves out the subject, so depending on context it could also be understood more generally, but by itself 使いません is just a polite negative statement, not a command or prohibition.

If you wanted to clearly say You must not use your smartphone during class, more direct forms would be things like:

• 授業中は、スマホを使ってはいけません。
• 授業中は、スマホを使わないでください。

So the original sentence sounds more like:

• a personal habit
• a classroom rule being stated gently
• a polite statement of behavior

rather than a strong direct prohibition.

This is a very common question.

• あいだ = during the whole period / throughout the time
• あいだに = at some point during that time

So in your sentence:

• 授業のあいだは、スマホを使いません。 = During class, I do not use my smartphone. = I refrain from using it for the whole class period.

Compare:

• 授業のあいだに、先生に質問しました。 = I asked the teacher a question during class. = At some point during class, that happened.

So あいだ focuses on an action or state continuing through the span, while あいだに often marks a single event happening within that span.

Yes, absolutely. 授業中は、スマホを使いません is very natural.

• 授業のあいだは = during class
• 授業中は = during class / in class

In many everyday situations, 授業中 may sound a bit more compact and natural.

Nuance:

• 授業のあいだ emphasizes the time span of the class
• 授業中 means in the middle of class / during class and is very common for rules and habits

For example:

• 授業中は寝ません。 = I don’t sleep during class.
• 会議中は電話に出ません。 = I don’t answer the phone during meetings.

So your original sentence is correct, but 授業中は is a very useful alternative to learn.

スマホ is the common shortened form of スマートフォン (smartphone).

This kind of shortening is extremely common in Japanese. In everyday speech, スマホ is much more natural than the full スマートフォン.

So:

• スマホ = casual, normal, everyday
• スマートフォン = full form, a bit more formal or technical

Even in polite sentences like this one, using スマホ is completely normal.

Yes. It is very natural.

Japanese often omits subjects when they are understood from context. If the speaker is talking about their own behavior, 私は is usually unnecessary.

So:

• 授業のあいだは、スマホを使いません。 is natural and complete.

If you add 私は, it becomes:

• 私は、授業のあいだは、スマホを使いません。

That is also correct, but it may sound more explicit than necessary unless you want contrast, such as:

• 私は授業のあいだは使いませんが、休み時間には使います。 = I don’t use it during class, but I do during breaks.

It can be either, depending on context.

Because 授業 has no article like a or the, and Japanese often relies on context, the sentence could mean:

• during class in general
• during a particular class
• as a personal rule whenever class is happening

Most naturally, without extra context, it sounds like a general habit or rule:

• During class, I don’t use my smartphone.

If you wanted to make it very specific, context or extra words would help:

• 今日の授業のあいだは = during today’s class
• この授業のあいだは = during this class

Yes. 使わない is the plain negative form, while 使いません is the polite negative form.

• 使わない = plain / casual
• 使いません = polite

So:

• 授業のあいだは、スマホを使わない。 = casual
• 授業のあいだは、スマホを使いません。 = polite

The meaning is basically the same. The choice depends on the situation:

• speaking casually to friends: 使わない
• speaking politely, writing, or answering in class: 使いません

Since your sentence is polite overall, 使いません fits well.