a thing or two

[redgiant]

know a thing or two know something about, be quite familiar

But I found these sentences difficult:
1.A peace movement has learnt a thing or two from Vietnam. (From Collins Dict)
2.They taught me a thing or two about the World History. (My own sentence)

1. Does it mean the peace movement studied a lot the case of Vietnam ?
2. They shared the World History they are familiar with to me, so I can grasp the subject well? or They shared their familiar subject, the world history, to us, without knowing whether I could understand it well?

[susiedqq]

"a thing or two" is used to express that a lesson has been learned about something.


I taught him a thing or two about manners.

I learned a thing or two about . . .

[SUDHKAMP]

know a thing or two know something about, be quite familiar

But I found these sentences difficult:
1.A peace movement has learnt a thing or two from Vietnam. (From Collins Dict)
2.They taught me a thing or two about the World History. (My own sentence)

1. Does it mean the peace movement studied a lot the case of Vietnam ?
2. They shared the World History they are familiar with to me, so I can grasp the subject well? or They shared their familiar subject, the world history, to us, without knowing whether I could understand it well?

No, it does not mean that if you know a thing or two about anything that you have studied a subject matter deeply. But just that you had an introduction to the subject where you learnt a few things/points about the subject matter. It also means discussing a few finer points.
The intent is that when a discussion or debate or some conversation takes place, you just discuss a few points and not the whole matter. And you discuss only a few points rather than going into details.

Ex. : The senior player told a thing or two about the game to juniors on his visit to the local club.

During the summit meeting, a thing or two were surely discussed about the present bout of terrorism all over the world, apart from Global Financial Crisis.

[Barb_D]

The phrase "I know or thing or two" or "learned a thing or two" is deliberate understatement to mean "I know a lot" or "I learned a lot."

Your expressions refer to how much has been learned, not how hard it was studied or how difficult was to teach.