was/ is

[Belly T]

he wrote his lessons with a very expensive pen
the pen which he wrote the lesson with is very expensive
or
the pen which he wrote the lesson with was very expensive

[Harry Smith]

Originally Posted by Belly T

he wrote his lessons with a very expensive pen
the pen which he wrote the lesson with is very expensive
or
the pen which he wrote the lesson with was very expensive

And what's your question?

[fiona bramble]

Originally Posted by Belly T

he wrote his lessons with a very expensive pen
the pen which he wrote the lesson with is very expensive
or
the pen which he wrote the lesson with was very expensive

Both are fine although I might stick with the past for parallelism

[Belly T]

The two are rewrited of the first sentence:
he wrote the lesson with an expensive pen

[Harry Smith]

Originally Posted by Belly T

The two are rewrited of the first sentence:
he wrote the lesson with an expensive pen

"He wrote with an expensive pen at the lesson." is better than those two.

Though you can say:The pen which I wrote with at the lesson was expensive. If you usually write with that evpensive pen at the lessons and you still have it you can also say: The pen which I wrote with at the lesson is expensive.

[Casiopea]

Originally Posted by Harry Smith

"He wrote with an expensive pen at the lesson" is better than those two.

Correction
in the lesson
during the lesson

All the best.

[Harry Smith]

Originally Posted by Casiopea

Correction
in the lesson
during the lesson

All the best.

Is "in the lesson" AmE or Canadian?

[Belly T]

No, I meant, you guys must rewrite the sentence with the clue given, starting with:
The pen______________

[fiona bramble]

Originally Posted by Belly T

No, I meant, you guys must rewrite the sentence with the clue given, starting with:
The pen______________

Yes, Belly_T, we know! Sometimes people get distracted by other things On that note, I think Harry & Casiopea may have missed "the lesson" meaning anyway...(???) I believe your sentence is referring to the actual paper lesson, what is usually called "an exercise" (here in Canada), or perhaps "a worksheet", so the preposition discussion is moot. (to be fair though, Harry, are you stating "at the lesson" is a BrE collocation?)
As to your question, to recap, is/was are both acceptable; "is" if it is still true; "was" if it was true then or to maintain tense consistency in the sentence as a whole!

[Harry Smith]

Originally Posted by fiona bramble

Yes, Belly_T, we know! Sometimes people get distracted by other things On that note, I think Harry & Casiopea may have missed "the lesson" meaning anyway...(???) I believe your sentence is referring to the actual paper lesson, what is usually called "an exercise" (here in Canada), or perhaps "a worksheet", so the preposition discussion is moot. (to be fair though, Harry, are you stating "at the lesson" is a BrE collocation?)
As to your question, to recap, is/was are both acceptable; "is" if it is still true; "was" if it was true then or to maintain tense consistency in the sentence as a whole!

Yes, I just wanted to know if "in the lesson" really means "during the lesson".
I must say I often come across to "at the lesson" meaning "during the lesson".