I have recently discovered this wonderful app for making stop motion animated movies on the iPad. It is free to download from the App Store but includes a number of in-app purchases such as sound effects and movie themes which you may wish to invest in. Students can simply draw a sequence of images on paper to photograph or build models using plasticine, Lego or pipe cleaners etc. Most recently, my AS students (who are currently studying a unit on immunity) animated clonal selection and expansion in B-lymphocytes (below), phagocytosis and the action of antibodies.