A Montessori school tucked away on the first floor of a Rockwood Street was briefly cleared of students Friday morning after fumes from chemicals being used to strip board on the second floor caused alarm. A Boston Fire spokesman posted via Twitter that crews arrived at 10:43 a.m. in response to a call about a strange odor. A solvent workers were using to peel off floor adhesive turned out to be the source. Hazardous materials experts said readings were negative. The Bilingual Montessori School of Boston, 61 Rockwood St., offers instruction in French and English.