Complex sentence: The GEMS project used extracurricular activities, role-playing and games, GEMS began in the sixth grade and worked for two years with boys and girls ages 12--14 in public schools in public schools in Goa, Kota and Mumbai.
Split into simpler sentences: The GEMS project used extracurricular activities, role-playing and games. This project began in the sixth grade and worked for two years with boys and girls between the ages of 12--14 in public schools in Goa, Kota and Mumbai.