This paper examines which rehearsal method (physical practice vs. mental practice) can better strengthen spatial memory. Participants were asked to learn four routes that navigated from starting points to destinations in four different maps. Then they were asked to rehearse the routes by using one of the following methods: 1) mental practice by simulating the routes in their mind; 2) physical practice by drawing the routes on papers; 3) physical practice by having index fingers trace the routes in air with eyes closed; and 4) physically practice by having index fingers trace the routes in air with eyes open. Finally, they verbally recalled the routes. The findings showed that physical practice with index fingers tracing the routes in air while keeping the eyes closed outperformed other rehearsal methods. Thus, tracing directions in air without any visual inputs can help participants to retain the visuo-spatial memory.