I am stumped too on this problem too

There is no escape. Everywhere you look you see this math problem go viral:

http://www.nytimes.com/2015/04/15/science/a-math-problem-from-singapore-goes-viral-when-is-cheryls-birthday.html.

I admit I am stumped too as this is hard because the clues seems to tell you... nothing:

Albert: I don’t know when your birthday is, but I know Bernard doesn’t know, either.

Bernard: I didn’t know originally, but now I do.

Albert: Well, now I know, too!

This doesn't fall into usual logic puzzles of clues... I can't easily put it into conditions or predicates then link them together.

Now, before you say everyone in Singapore is smart in math but all Americans all bad. Just what "math" are we dealing with here? This is some logic puzzle. Logic isn't only appearing in math you know.

Why did Hamlet see his dad's ghost? If Hamlet's dad is dead he may become a ghost then Hamlet may see it! (A quick example of logic in other place)

It is perfectly fine if you can't tell Cheryl's birthday. This seems not to be a typical... not even a good problem that test ability to link logical pieces together.

But it isn't ok for American students to not even know how to add some fractions by 5th grade or so.

Just grab Cheryl's ID card is the quickest way to find her birthday if she isn't telling.