Sentence:  Robinson told Policemen James Jones and Morgan Lloyd of the Wabash avenue district that 10 youths boarded his south bound express bus in front of Dunbar Vocational High school , 30 th street and South Park way , and <WSD>began</WSD> `` skylarking '' . 
Meaning of the word marked with <WSD> tags:  take the first step or steps in carrying out an action