We conducted experiments with sound using elastic bands and plastic trays and different sized bottles filled with water. We have learnt that sounds are created by vibrations. The louder the sound, the bigger the vibration. You can change the pitch of a sound in different ways, depending on the type of instrument you are playing. The size of the vibration is called the amplitude. Louder sounds have a larger amplitude, and quieter sounds have a smaller amplitude. For example, if you are playing the xylophone, striking the smaller bars with the beater causes faster vibrations and, so, a higher pitched note. Striking the larger bars causes slower vibrations and produces a lower note.