The applet below presents a variant of the Shuttle Puzzle and helps check one's understanding of the latter. As in the puzzle itself, you are required to draw horizontal shuttles joining vertical poles. The difference between the two applets is two-fold. First, the number of shuttles you are required to draw is specified at the bottom of the applet. Second, you draw the shuttles purposefully. Note that there are two small vertical arrows: a downward arrow at the top and an upward arrow at the bottom. The arrows set up the puzzle: you have to draw the shuttle(s) so that it creates an itinerary from the top of the pole pointed to by the downward arrow and ends at the bottom of the pole pointed to by the upward arrow."
(To draw a shuttle drag the cursor from one pole to another.)