A Preble County teacher accused of having a sexual relationship with a student has changed his plea.  31-year- old Garrett Stringer-Smith pleaded not guilty to sexual battery charges in March and was indicted on all 10 counts.  Stringer-Smith has now changed his plea, pleading guilty yesterday to all 10 counts of sexual battery, according to Preble County Common Pleas Court documents. Stringer-Smith was a teacher at Twin Valley Community Schools and is accused of having an inappropriate relationship with a student. The former Band Director was arrested in February after the child reported the relationship to a school resource officer.  He is facing a maximum sentence of 50 years in prison and is expected back in court on Dec. 3.