The National Film Board of Canada recently released a fantastic new iPad app for creating stop-motion videos. NFB StopMo Studio allows you to take a series of pictures and stitch them together to create a stop-motion video. Like similar apps you can adjust the number of images that are displayed per second.
Where the app really shines is in the post-image editing options. NFB StopMo Studio allows you to use multiple soundtracks in your video. You can also draw or type on top of each image in your video.
NFB StopMo Studio could be a great app for students to use to create short claymation-style videos to animate a story that they have written in your classroom.