The teacher circumscribed the play area for the children with chalk on the floor.

circumscribed 是动词 circumscribe 的过去式。circumscribe 由前缀 circum-（表示"环绕、周围"）和动词 scribe（写、画）组成，字面意思是"在周围画线"，引申为"划定界限、限制范围"的意思。