INDIANAPOLIS — USA Football says nine of the nation’s 10 largest school districts have adopted its Heads Up program, up from six of the 10 largest districts last year.

The program is designed to teach better tackling techniques in youth and high school football to make football safer.

Public schools in New York, Los Angeles and Chicago each jumped on board along with 16 of the 20 largest districts in the nation. A year ago, only 11 of the top 20 participated.