A standard rudiment in percussion musicianship.

A single-stroke roll incorporates bouncing the drum stick once with each hand. The drummer must control the timing to create a clearly audible stroke with balance between the two hands. 

A common percussion exercise to teach single-stroke roll timing:

R L  R L | R L  R L ||

1 + 2 + | 1 + 2 + || 

Make sure you practice starting out from both the left and right hands. This will be useful later on when you begin to cover paradiddles.

Thanks to Alpheus for the node template. Iron Noder 2017