My best selling unit on TpT is my States of Matter Unit. Many teachers have purchased this unit and have had much success with it in their classroom. I contribute this to my "hands-on" approach to teaching Science. I think a lot of teachers like using hands-on activities in their classroom, but don't really know where to start.
Teachers have sent me emails requesting more Science units. I am slowly but surely getting those up. I posted a Sound mini-unit late last night. I call this a mini-unit because the unit isn't complete like my States of Matter unit. This sound unit has lots of hands-on activities and ideas, but does not contain a study guide and final assessment for the unit. It's just not comprehensive.
Check out this unit! I think your kids will love the sound centers in which this kids learn about the principles of sound through hands-on experiences.