shàngkè de shíhou, wǒ zǒngshì yòng qiānbǐ zuò bǐjì.

In 上课的时候, 的 links the action 上课 (to attend class / be in class) to the time word 时候 (time, moment).

So the pattern is:

verb / phrase + 的 + 时候
= when ... / at the time of ...

Examples:

• 吃饭的时候 = when eating / during mealtime
• 睡觉的时候 = when sleeping
• 上课的时候 = when in class

In English, we often say when class starts, during class, or in class, but Mandarin often builds this kind of time phrase with ...的时候.

Yes. A very common shorter version is:

上课时

Here, 时 is a more concise, slightly more written/formal version of 时候.

So these are both natural:

• 上课的时候，我总是用铅笔做笔记。
• 上课时，我总是用铅笔做笔记。

The version with 时候 sounds a bit more conversational and full.
The version with 时 is shorter and often feels more compact.

上课 literally means something like attend class or be in class.

It can refer to:

• students having class
• teachers giving class / teaching a class, depending on context

In this sentence, because the speaker says 我总是用铅笔做笔记, it sounds like the speaker is a student, so 上课的时候 is best understood as during class or when I’m in class.

Mandarin often puts time expressions before the main action.

So this pattern is very common:

Time + subject + adverb + verb phrase

In this sentence:

• 上课的时候 = time
• 我 = subject
• 总是 = adverb
• 用铅笔做笔记 = main action

That gives: 上课的时候，我总是用铅笔做笔记。

This is very natural in Chinese.
English can also front time expressions, but Chinese does it even more regularly.

总是 is an adverb, and in Mandarin, adverbs usually come before the verb phrase they modify.

So:

• 我总是做笔记 = I always take notes
• 我总是用铅笔做笔记 = I always use a pencil to take notes

The adverb 总是 modifies the whole action, not just one small part of it.

A useful pattern is:

subject + adverb + verb phrase

Examples:

• 我常常去图书馆。
• 他已经吃饭了。
• 我们都喜欢中文。

Both can describe repeated actions, but they are not exactly the same.

• 总是 = always, with a strong sense of consistency
• 常常 = often, less strong

So:

• 我总是用铅笔做笔记。 = I always use a pencil to take notes.
• 我常常用铅笔做笔记。 = I often use a pencil to take notes.

总是 can also sometimes suggest a habitual pattern that the speaker notices strongly, and in some contexts it can sound slightly emotional:

• 他总是迟到。 = He is always late.

But in your sentence, it is simply always.

Yes, 用 here means to use and often corresponds to English with when talking about tools or instruments.

So:

• 用铅笔 = using a pencil / with a pencil
• 用手机 = using a phone
• 用中文说 = say it in Chinese / using Chinese

In Mandarin, the structure is often:

用 + tool / method + verb

Examples:

• 用筷子吃饭 = eat with chopsticks
• 用电脑工作 = work on a computer / use a computer to work
• 用铅笔做笔记 = take notes with a pencil

So even though English may prefer with, Chinese often uses the verb 用.

做笔记 is the standard expression for take notes.

Literally:

• 做 = do / make
• 笔记 = notes

But you should learn 做笔记 as a set phrase, because languages often package actions differently.

Compare:

• English says take notes
• Mandarin says do/make notes

This is very common in Chinese:

• 做作业 = do homework
• 做饭 = cook / make food
• 做梦 = dream

So even if the literal wording feels unusual from an English point of view, 做笔记 is exactly the normal way to say it.

Sometimes 写笔记 can be understood, because notes are of course written, but 做笔记 is the more standard and idiomatic expression for take notes.

A simple way to think about it:

• 做笔记 focuses on the activity of note-taking
• 写笔记 focuses more directly on the act of writing

In most beginner situations, if you mean take notes, use 做笔记.

The comma separates the time phrase from the main statement.

So the structure is:

上课的时候， | 我总是用铅笔做笔记。

This kind of comma is very common in Chinese when a longer phrase comes first, especially:

• time phrases
• condition phrases
• topic phrases

It helps readability, much like in English:

• When I’m in class, I always take notes with a pencil.

In very short sentences, punctuation can sometimes be more flexible, but here the comma is natural and standard.

Sometimes yes, but it depends on context.

Chinese often omits subjects when they are already clear. So if everyone knows you are talking about yourself, you might hear:

上课的时候，总是用铅笔做笔记。

However, in a standalone example sentence, keeping 我 is better because it is clear and complete:

上课的时候，我总是用铅笔做笔记。

So:

• with 我 = clearer, more neutral for learning and formal completeness
• without 我 = possible in conversation if the subject is obvious

In 时候, the second syllable hou is usually read in a neutral tone.

So instead of a strong fourth, third, etc. tone, it is light and unstressed:

• shíhou

This is very common in Mandarin. Many second syllables in frequent words become neutral in actual pronunciation.

Examples:

• 时候 = shíhou
• 东西 = dōngxi
• 知道 = zhīdao

So the missing tone mark on hou is not a typo; it shows the neutral tone.

It describes a habitual action.

The clue is 总是, which means always. That tells us the speaker is talking about what they regularly do in that situation, not just what happened once.

So the sentence means something like:

• whenever class is happening, this is my usual behavior

This is one reason Mandarin often does not need a tense ending like English does. Words such as 总是, time phrases, and context tell you whether the action is habitual, ongoing, completed, and so on.