jīntiān shàngkè de shíhou, qǐng bǎ kèběn fàng zài zhuōzi shàng, xiān kàn hēibǎn, zài zuò bǐjì.

上课的时候 means when class is happening or during class.

• 上课 = to have class / to be in class / to attend class
• 时候 = time, moment
• 的 links the verb phrase 上课 to 时候

A very common pattern is:

[verb / verb phrase] + 的时候 = when ... / during ...

So:

• 吃饭的时候 = when eating / during the meal
• 下雨的时候 = when it rains
• 上课的时候 = when class is in session

You usually need 的 in this pattern. A shorter, slightly more formal version is 上课时.

In Mandarin, time words often come near the beginning of the sentence, before the main action.

So it is very natural to say:

• 今天上课的时候，...
• literally: today, during class, ...

Chinese often goes from time → situation → action.

That is why 今天 appears first: it sets the time frame for everything that follows.

Yes, but that is completely normal.

This sentence is giving instructions, so the subject is understood as you, everyone, or the students. Mandarin often leaves out subjects when they are obvious from context.

So the full idea could be something like:

• 今天上课的时候，你们请把课本放在桌子上，先看黑板，再做笔记。

But adding 你们 would usually be unnecessary.

请 makes the instruction polite. In this sentence, it works like please.

So:

• 请把课本放在桌子上。 = Please put your textbook on the desk.

But 请 has a broader meaning than English please. It can also mean to invite or to request, depending on context.

For example:

• 请进 = please come in
• 请坐 = please sit
• 我请你吃饭 = I’m treating you to a meal / I invite you to eat

Here, it is simply a polite instruction marker.

This is the 把-construction, which is very common in Mandarin.

Pattern:

把 + object + verb phrase

It is used when you want to focus on what happens to the object.

Here:

• 课本 is the object
• the action is 放在桌子上 = put it on the desk

So:

• 请把课本放在桌子上
• literally: Please take the textbook and place it on the desk

This sounds natural because the textbook is being moved to a new location.

Without 把, the sentence would not sound as natural for this kind of instruction.

Sometimes yes, but it changes what sounds natural.

For this exact command, 把 is the most natural choice:

• 请把课本放在桌子上。

If you remove 把, you would usually need a different structure, such as:

• 请把课本放好。
• 请将课本放在桌子上。 (more formal, with 将)

A plain form like 请课本放在桌子上 is not correct.

So for learners, it is best to treat 把课本放在桌子上 as the normal pattern here.

It breaks down like this:

• 放 = put / place
• 在 = at / in / on (introduces location)
• 桌子上 = on the desk

So:

• 放在桌子上 = put it on the desk

In 桌子上:

• 桌子 = desk / table
• 上 = on top of

This 上 is a localizer, which tells you the position.

So the structure is:

verb + 在 + place + localizer

Examples:

• 放在椅子上 = put it on the chair
• 写在纸上 = write it on the paper
• 挂在墙上 = hang it on the wall

They are the same character, 上, but they are doing different jobs.

1. 上课

   • here 上 is part of the verb 上课
   • 上课 means to have class / attend class

2. 桌子上

   • here 上 is a location word
   • it means on top of

So even though both are pronounced shàng and written with the same character, they do not mean exactly the same thing in these two places.

This is very common in Chinese: the same character can have related but different uses.

Yes, both are pronounced zài, but they are different words.

• 在 = at / in / on / to be located at
• 再 = then / again / after that

In this sentence:

• 放在桌子上 → 在 shows location
• 再做笔记 → 再 shows the next step: then take notes

So:

• 在 answers where
• 再 answers what next

This is a very common confusion for learners, because the pronunciation is the same.

先...再... means first... then...

It shows sequence.

In the sentence:

• 先看黑板，再做笔记。
• First look at the blackboard, then take notes.

This pattern is extremely common in Mandarin.

Examples:

• 先洗手，再吃饭。
  • First wash your hands, then eat.
• 先写作业，再玩。
  • First do your homework, then play.

A close alternative is 先...然后..., but 先...再... is very common and natural.

Because Chinese often keeps instructions short and direct.

• 看黑板 = look at the blackboard
• 做笔记 = take notes

In classroom instructions, short verb-object phrases are very natural.

English often needs extra words such as at in look at the blackboard, but Mandarin usually does not need an extra word here:

• 看黑板 literally: look blackboard
• natural meaning: look at the blackboard

Yes, literally it looks like do notes, but 做笔记 is the normal expression for take notes.

This is a fixed collocation:

• 做笔记 = take notes
• 记笔记 = also very common, meaning take notes
• 写笔记 = write notes, but often sounds a bit more literal

So learners should not translate word-for-word from English. Just remember that 做笔记 is a standard Mandarin way to say take notes.

It can mean slightly different things depending on context.

Common uses:

• 学生上课 = students attend class / are in class
• 老师上课 = the teacher teaches class
• 开始上课 = class begins

In 今天上课的时候, the meaning is during class today or when class is going on today.

So the exact English wording depends on context, but the basic idea is connected to class time.

Because Chinese nouns often appear without either one when the meaning is general or obvious from context.

Here 课本 simply means textbook(s) or the textbook depending on the situation.

Chinese does not require articles like a or the, and it does not always mark plurals.

If you wanted to be more specific, you could say:

• 一本课本 = one textbook
• 这些课本 = these textbooks
• 你们的课本 = your textbooks

But in a classroom instruction, plain 课本 is perfectly natural.

Yes. They help separate the instructions into clear steps.

The sentence has a natural rhythm:

• 今天上课的时候，
• 请把课本放在桌子上，
• 先看黑板，
• 再做笔记。

These pauses make the instruction easier to follow.

In written Chinese, punctuation is important because long strings of characters can otherwise be hard to parse. The commas here show:

1. the time setting
2. the first instruction
3. the second instruction
4. the final step

So they are not random—they reflect the structure of the sentence.