Didn't know that was happening, huh? There's an art contest called "Doodle 4 Google." Kids send Google a drawing in response to the prompt, "What I'd like to do someday ..." It's for kids from kindergarten through 12th grade. Last year, the contest had 33,000 entries. From the New York Magazine:

Along with the submission, the contest's initial Parent Consent Form asked for the child's city of birth (not current city, mind you), date of birth, the last four digits of the child's Social Security number, as well as complete contact info for the parents. Bob Bowdon, who directed The Cartel, a documentary about corruption in the public-school system explained the significance:

You see what Google knows and many parents don't know is that a person's city of birth and year of birth can be used to make a statistical guess about the first five digits of his/her Social Security number. Then, if you can somehow obtain those last four SSN digits explicitly -- voila, you've unlocked countless troves of personal information from someone who didn't even understand that such a disclosure was happening.

Just over a day after the FTC was alerted to this policy, Google is no longer collecting the last four digits of entrants' Social Security numbers.

Here's one of the winning entries from last year -- Makenzie Melton, grade 3, from El Dorado Springs, Mo.

See other winning entries from last year here

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