(Portland, OR)  --  Authorities say a licensed school teacher is accused of holding up a Plaid Pantry in northeast Portland.  Ian William Mandis of Portland is currently on leave from his temporary math teacher position with the Parkrose School District.  Mandis is facing a second-degree robbery charge after being accused of displaying a gun after entering the store on Northeast Glisan early Sunday morning and demanding cash.  Police say they seized a replica gun from Mandis' home.