And I hope, as we covered some very serious subjects and we watched the world change, I hope you had some fun, too.

WHITEHOUSE: Press Briefing

As we talk, it becomes apparent that behind Mr. Jacobs's boyish demeanor and gentle humor are a serious nature and broad knowledge of subjects suggestive of someone much older.

WSJ: Paul Jacobs | Great Music Needs No Apology | Cultural Conversation by Barrymore Laurence Scherer

The male student said he appreciated the president's humor but also felt that serious subjects were discussed and would help begin a better dialogue between the two countries.

CNN: Not an ordinary Obama town hall

The early citizens of the net (or netizens) took their netizenship serious, and built homepages about themselves and subjects they were experts in.

FORBES: Resurrecting 'The Deleted City' Of The Internet's Early Pioneers

So far officials of the National Institutes of Health say they've seen no serious side effects in clinical trials and that study subjects who have been immunized have generated a good response.

CNN: Poll: Majority of adult Americans don't want H1N1 shot

Lear noted that despite tackling some serious subjects in her work, Franklin always stayed cheery and positive.

WSJ: Bonnie Franklin, 'One Day At a Time' star, dies

Copyright infringement is a serious matter that violates U.S. copyright law and subjects infringers to criminal and civil liability.

FORBES: Verizon Has Already Started Warning Pirates

And since they've returned, their interest has turned to serious subjects.

CNN: Recovery: Stars come out for WTC victims

In comparison to antitrust cases, regulatory agencies are subject to greater outside review, receive more serious oversight from elected officials, and have greater expertise in the subjects within their purview.

FORBES: Litigation, Regulation, Antitrust: Bad Bets For An Innovation Economy

He also said there was a serious problem in recruiting teachers in key subjects such as maths and physics.

BBC: Teacher vacancies rise a quarter