Microsoft is expanding a program that gives schools the ability to prevent ads from appearing in search results when they use its Bing search engine.

Bing search engine (Dan Alexander,Townsquare Media NJ)

The program, launched in a pilot program earlier this year, is now available to all U.S. schools, public or private, from kindergarten through the 12th grade.

The program is meant to create a safer online environment for children, but also promote use of Bing, which trails market leader Google Inc.

Redmond, Wash.-based Microsoft Corp. is also giving away a first-generation Surface tablet computer to schools where community members sign up to use the ad-supported version of Bing outside of the school. Sixty parents and friends who do 30 Bing searches a day could earn their school a Surface in a little over a month.

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