This week I am introducing the concept of sound to my 3rd grade students.  In order for them to first get engaged, I am going to use the website: The Sound Site http://www.smm.org/sound/nocss/top.html. 
I will play some sounds to have the students try to figure out what object is producing that sound.  Following this introduction, I will ask the students why do they think they are able to hear that specific noise.  By asking them this question, they will start to brainstorm a hypothesis of what creates sound.