The Seventh-day Adventist Church operates Sabbath Schools for all age groups in almost every church around the world. The lesson is designed to follow the same Bible study and changes themes each quarter. Some churches offer alternative classes to meet specific needs in their congregation or community. Sabbath School is about a 70-minute exercise usually conducted before or after the worship service in the local church. There are classes for each age group: infants, children, youth and adults.