A Pan Flute (or panpipes) is a musical instrument made from a series of pipes of different lengths tied together. The player blows across the top of the pipes to make the notes.
Try making your own Pan Flute out of straws. Take some straws and lay them flat side by side on a table with the ends lined up. Tape them together at one end. At the other end cut diagonally so that the straws are all different lengths, from long to short. Add extra tape if needed to make your instrument stronger.
Now hold your pan flute vertically with the straight edge at the top. Blow across the open straws. You should hear that long straws make a lower note than high straws. A real pan flute has the ends of the pipes blocked up. Cover the ends of your straws with your fingers and blow again. Can you hear that the note is lower when the pipe is blocked?