KS 4: A search on the physics of bird song throws up the range of research into understanding its incredible intricacies. Brainstorm with the class what areas of physics are relevant and you might come up with sound production, resonance, slowing down the sound to analyse the patterns. How can bird song be used to teach a bit of physics? Resonance is a perfect example - since the Millennium Bridge has been corrected, what better than the synchronised rhythms of South American ovenbirds? The male begins singing and the song of the female is miraculously driven by the male. Demonstrate driven oscillators by hanging two pendulum bobs or two bouncy balls from a string stretched between two points. Start one oscillating. The energy is transferred from one to the other as each one drives the other and swings in turn. The alternate swinging can continue for some time. For these birds, it is slightly more complicated in that instead of controlling the female's syrinx, the male and female notes come in different ratios. A wonderful mathematical pattern is created as the muscles of each bird vibrate together. All students will have experienced resonance from playing on a swing or making a wine glass sing, and birds all around them demonstrate it too, some in more complex ways than others.