PERCUSSION: WOODBLOCK

A single toned woodblock is essentially a small piece of slit drum (or a cuboid-shaped block of hard wood) made from a single piece of wood and used as a percussion instrument. It is held in one hand struck with a beater stick, making a characteristically percussive sound.It is very effective when it is played with a pair of drumsticks. 
http://en.wikipedia.org/wiki/Wood_block
http://www.curriculumonline.ie/en/Primary_School_Curriculum/Arts_Education/Music/Music_Teacher_Guidelines/Appendix/How_to_hold_and_play_some_percussion_instruments/How_to_hold_and_play_some_percussion_instruments.html?print=1

http://www.youtube.com/watch?feature=player_embedded&v=H_M1Yz9SBfs

 http://www.youtube.com/watch?feature=player_embedded&v=_O5wGp39C8s

The wood block, or two-tone wood block, is a percussion instrument that creates sound when hit together due to a resonating chamber.

Two-Tone Wood Block

As the name suggests, this instrument can produce two different tones. 

It is held by the handle and each side is struck with a wooden beater.

http://www.ehow.com/video_4952556_percussion-instruments-wood-block.html

The Paul Laurence Dunbar High School Percussion in 2006 

performing visual drumming using woodblocks and black light.