A man honored as among the best teachers in Utah pleaded guilty Thursday to felony sex charges involving 11 students at his suburban classroom.

Frank Laine Hall, 37, who taught first grade in the Salt Lake City suburb of Riverton until his arrest last March, could get up to 30 years to life in prison, prosecutor Rodwicke Ybarra said.

Hall pleaded guilty to 10 counts of attempted aggravated sex abuse of a child and one count of sex abuse of a child in a plea agreement that dismissed five other counts of aggravated sex abuse of a child, Ybarra said.

The agreement will ensure that he must register as a sex offender for life, Ybarra said.

In court Thursday, Hall admitted he touched the students inappropriately, Ybarra said.

The former teacher didn't respond to an e-mail Thursday sent through his animated class Web site, which is still up but appears dated. His lawyer, David Finlayson, refused to take any calls from The Associated Press.

Hall remains free on $500,000 bail until his sentencing Nov. 14.

Hall was accused of putting his hand inside the pants of three girls at Rosamond Elementary School in Riverton. Then eight other students came forward with similar accounts, Ybarra said.

Authorities were tipped by the parents of one student, and school officials said they immediately barred Hall from the classroom.

Hall received a Huntsman Award for Excellence in Education in 2006, an honor for being one of the best teachers in Utah.

Huntsman Corp., the nation's fifth-biggest chemical manufacturer, earlier this year had a Web page posted with Hall's photograph.

At the time, Huntsman Corp. said it had no immediate plan to rescind Hall's award, but his profile has disappeared from the corporate Web site, replaced by a slate of 2007 winners.

On Thursday, a spokesman for company Chairman Jon Huntsman Sr., Jannie Spader, said nobody at the company was aware of Hall's guilty plea, but that an advisory board probably would revisit Hall's award.