Despite the diverse selection of animation software we have only one that we highly recommend: Digicel Flipbook. It is no surprise that this one was used even at Disney: Flipbook emulates the process of creating traditional animation with tremendous precision. You can draw keys and make inbetweens right in your project, — or you can scan frames on paper and easily adjust their timing.
It is even more convenient for education: if you show your assignment in Flipbook, the teacher can change timing, leave marks and make corrections right on your drawings without harming the original. In the end of the session you receive the file with everything , that is necessary to complete the assignment. We cannot recommend this software enough.
You can download Flipbook Digicel from the official web-page: http://www.digicelinc.com/download/downloads.htm