The 6 bottles are then numbered and you blow on your bottle when your number comes up. So if you're bottle #1, you simply blow on your bottle the number of times and in the order written on the bottle. You and 5 others at the party or school drink to the line and follow the instructions to play a tune.
Bottle one (C): 1- 2-
Bottle two (G): 3- 4-
Bottle three (A): 5- 6-
Bottle two (G): 7- 8-
Bottle four (F): 9- 10-
Bottle five (E): 11- 12-
Bottle six (D): 13- 14-
Bottle one (C): 15- 16-
Each bottle would have the number of notes in the melody with their turn to play circled. So bottle two would say:
1 2 (3) (4) 5 6 (7) (8) 9 10 11 12 13 14 15
That's Twinkle Twinkle Little Star. Could also go with more bottles and have the kids play sequences of chords.
Or you could just make them play a chord. The kids blowing on them at random would play an original melody within that chord.
The chord thing would probably be a lot easier. Be kind of fun to see a room full of kindergardeners playing music on their juice break.