A Pinocchio estimation game 

Is Pinocchio lying?
Examples: 
"The average life span in the US is two billion seconds." "The total number of miles driven in the US each year is greater than the national debt in pennies." 
Making up statements  
You can use any source of numbers. Stuff you already know. This
site, government web pages, and any other stuff on the web or off.
You can use some fact directly. Or combine it with others. Or describe it in a bizarre way (average life span in seconds, cost of a slice of pizza in lifetime salary). Or the Pinocchio can just make up a question, and estimate hir own answer. You may allow the Pinocchio to choose how many factors of ten accuracy the statement has. Or you can just use one factor of ten. Or you can all decide together, maybe ahead of time.  
Guesstimating  
You can use stuff you know.
You may decide to permit using some other reference material, perhaps even the web.  
Deciding what is "right"  
The players decide together.
With statements based on reference numbers, you can just check the numbers and any math.
 
Other  
It can be fun to have "players" which are teams of more than one person.
You may wish to treat numbers from unreliable sources, such as television news, politicians, and even newspapers, as Pinocchio estimates. If the number seems really wrong... it may well be. 
Pinocchio is a wooden boy whose nose grows when he lies. Here is The Adventures of Pinocchio, a translation of the Italian children's book by Carlo Collodi/Lorenzini (18261890). Here are other Project Guetenberg mirrors.
The Pinocchio Game. We also plan to implement interactive
games expressly designed to develop QR skills. One computermediated
game enables students to exercise their mathematical skills and become
familiar with the dimensional calculator and computer almanac while
experiencing the flavor of QR problem work. Each player in turn
becomes Pinocchio or the "proposer" andusing the information in the
computer almanacmakes a supposedly "factual" statement. This
statement might be based directly on an entry in the data base combined
with a bizarre scaling, e.g., The average life span in the US is two
billion seconds. It might be based on a combination of database
entries, e.g., The total number of miles driven in the US each year is
greater than the national debt in pennies. Each of the other players
has to decide whether the statement is true or a lie, i.e., inaccurate
by a factor of 10 or more (or by an amount chosen by the players.) The
proposer gets one point for each incorrect choice made by a player. In
an alternate version, the computer proposes the statements (based on
the almanac data.) In one variant of this version the players may use
the almanac to respond; in another, their responses must be based on
their own estimates. In either case, the computer can offer hints and
"explain" the process used in developing its "factual statements".
This mode of play is particularly effective when used with teams. The
software for the computergenerated version will contain a complexity
measure that can be set to provide statements suitable for students at
different age and skill levels.
 Quote from a personal communication from Wally Feurzeig.  Game credited to George Lukas (UMass Boston). 
Comments encouraged.  Mitchell N Charity <mcharity@lcs.mit.edu> 
Doables: I'm not sure "Pinocchio" ideally characterizes the game. Additional statement examples. Collect pointers to "number" resources on another page. Cleanup draft. I'm not sure about the tactical dynamics of the accuracy choosing. I'd be nice to better integrate the error bars into the weave of the game. And perhaps a variant with confidence level rather than binary estimates. History: 2003Feb03 Repaired links  2 replaced. 2001Mar15 Changed "Pinnochio" to "Pinocchio". Ouch. Thanks to a reader for catching it! 2001Feb18 Created. First draft.