Share your thoughts on my GMAT journey

Firstly, if you've been getting 630 in your practice tests then you ARE a smart person. I suspect that you are now at the stage of of feeling like poop every time a CR question comes up. I got the same way with DS on the quants. Just remember that there is no difference between critical reasoning and having an argument with your friends over a friendly beer.

For me, critical reasoning questions are about eliminating choices rather than spotting the correct one right away.

I took this example from the CR section of the forums:

Learning how to build a nest plays an important part in the breeding success of birds. For example, Dr. Snow has recorded the success of a number of blackbirds in several successive years. He finds that birds nesting for the first time are less successful in breeding than are older birds, and also less successful than they themselves are a year later. This cannot be a mere matter of size and strength, since blackbirds, like the great majority of birds, are fully grown when they leave the nest. it is difficult to avoid the conclusion that they benefit by their nesting experience.

Which one of the following, if true, would most weaken the argument?
(A) Blackbirds build better nests than other birds.
(B) The capacity of blackbirds to lay viable eggs increases with each successive trial during the first few years of reproduction.
(C) The breeding success of birds nesting for the second time is greater than that of birds nesting for the first time.
(D) Smaller and weaker blackbirds breed just as successfully as bigger and stronger blackbirds.
(E) Up to 25 percent of all birds are killed by predators before they start to nest.

So firstly what is the underlying argument of the passage... I read it to be "as black birds get better at nesting, through experience over time, they are more successful at breeding".

Check the question again ... Which one of the following, if true, would most weaken the argument?

Weaken is the crucial word here. Now look for arguments that strengthen the passage as they will be the easiest to spot.

Rule out C. C would suggest that the passage is correct.

Now check for answers that have nothing to do with the argument.

Rule out D and E. They make no mention of nesting practice in relation to breeding ability.

At this point you have given yourself a 50/50 chance of getting the answer.

Look closely at A. While it does talk about the nesting abilities of blackbirds it is comparing them to other species rather than to different members of the same species. It neither strengthens or weakens the argument.

So the Answer must be B. And it is. It says that it is their ability to lay eggs that can hatch that increases over time and with maturity, and that leads to better breeding ability. Not, as the passage suggests, their ability to build better nests.

This is a somewhat difficult question, where you need to find the statement that casts most doubt on the conclusion of the passage rather than outright disagreeing with it. The method I used however works for me on all CR questions.