DO SI THREE 
Linda Leslie (via Chart Guthrie)
Three facing three in a line (triples facing either up or down the set).

Point out that in each triple there is one inside person (in the middle) 
and two outside people (on the ends). Each person is standing next to 
one or more partners and facing someone who is not their partner, their 
neighbor.  Join hands in circles of six people, we now have 2 inside 
people and 4 outside people.

The dance:

A1 Circles of 6 circle left, circle right back to place

A2 Outside 4 do si do your neighbor, Inside 2 do si do your neighbor

B1 Outside 4 right elbow swing your neighbor, Inside 2 right elbow swing 
   your neighbor

B2 With your partners go forward and back, pass your neighbor by the 
  right shoulder, don't turn around, there is your next neighbor.


CHART SEZ:

I always explain that when you pop out at the end you  need to turn 
around and wait one round of the music.

This dance almost always works for me. It works well with mixed ages and 
is a good way to introduce the concept of progression.