Made by whom ? I challenge the accuracy of any of those studies, especially the one done by Nature (yes, I've read all about it).
And I simply cannot accept that Wackypedia be qualified as "factually" accurate, in light of two things :

1) on Wackypedia, the "Truth" is defined "by consensus" - meaning that if there are enough nutjobs that agree that the Earth is flat, then flat it is. That attitude totally disregards anything even remotely related to fact.

2) Wackypedia has a long, documented history of editor tactics and super-user backroom dealings that would make a cigar-chomping illegal bookie jealous with envy. I simply cannot place any amount of trust in any organization whatsoever that is incapable of respecting its own editorial guidelines.

That said, I use Wackypedia from time to time. I deal with it the same way I would deal with choosing to drive down a dark alley at night in the bad part of town : I do it carefully and check everything.

There is good information on the W, as long as that information has been entered by people who know what they are saying, and as long as no super-editor has a personal biais against the author of the article.

So you tell me, which articles are those exactly ?

We know from studies and reviews that Wikipedia is markedly MORE factually accurate than traditional, editorially-reviewed encyclopedias. Go find some articles about subjects you know well and review them for accuracy right now, you will find them to be impeccable. It also strains the bounds of credibility that a student who is sufficiently interested and motivated about their own learning to research a subject on Wikipedia would fail to at least outperform their peers. This is clearly a case where an authority figure trying to preserve their job and reputation is scapegoating the Internet for the failures of their own educational system.

Students get knocked when passrates increase (exams too easy etc...) and again when they fall (lazy, poor research etc...). They can only do what they are taught and is put in front of them.

I agree with Pete and Martin that this is an old problem. When I went to school, formal reference texts such as encyclopedias and journals were the 'preferred' reference. We were taught how to cite a web site, but doing so would not help our marks.

I also agree that it sounds like a scapegoat. Was a study done to determine that the internet is to blame, or is this only conjecture? The irony...

Regarding Martin's statement: 
"I wonder when anyone will ask the question if it might be the teachers fault."

It seems they are - or, rather than the 'teachers', they are blaming the lack of information taught to students regarding research. Heck, here in the states they would do the students a huge favor by teaching them the perils of credit card use in an economics class. Sadly they don't.

In the good old days, it was the pupils fault. They where "lazy". Then the modern views corrected this wrong view and told us that it is all society`s fault. But now, fortunately we are all wiser again: now we know it is all due to Wikipedia being a sloppy patchwork of infotainment. I wonder when anyone will ask the question if it might be the teachers fault. I am a physicist, and I make aliving of giving auxiliary maths training to pupils. Guess what: They do not understand the exact same points that we did not understand, and in school they are being tought the same way we where being taught. But who am I to blame teachers bashing media they do not properly understand?

So what! In the long term I would expect pass rates to fall 50% of the time.

Well I would if standards remained at the same level, rather than falling faster than a lead balloon in a vacuum.

(And yes, I *know* a feather would accelerate just as quickly in a vacuum, which is more than most of today's GCSE Physics students would).

This isn't just a Wackypedia related problem. One could make the same argument about the media.

Critical thinking hasn't been taught or encouraged for decades.