Students work together in pairs - facing each other.

Both students hold out their right hand - palm up.

Both students hold out their left hand  - palm down - above their partner's extended right hand.

Both students move both hands (right up - left down) to strike their partner's hands in a vertical clapping motion.  Clap-clap-clap.

Both students now flip both hands over - so that the left hand is palm up and the right hand is palm down.  (They will also need to make a minor adjustment to the position of their hands in relation to their partner's hands - so that they can move their hands in a vertical clapping motion.)

Once students are proficient, it is easy enough to move on to a variety of rhythms that combine partner-clapping and ordinary clapping.