I recently found another app I love to use with my kids. This app is called Jelly Band and is great for teaching arranging and layering of ostinati. I have used this app with my part time learning support classes who have been immediately successful with it, as well as with my older students. They enjoy arranging and recording their own songs. So fun, so easy, and a quick way to teach arranging! I'd give it four stars! PLUS IT'S FREEEEE!