Psion's spreadsheet app, Sheet, is a powerful tool for the manipulation of data. It contains a vast array of mathematical, financial and scientific functions, and can create graphs from the data in a number of styles, which Microsoft's Pocket Excel cannot do. The only disadvantage is that graphs cannot be printed directly, but if you take a a screen dump (Psion- ctrl-shift-s), the graph is copied as a .pic (picture) file which can be viewed and printed from a graphics program such as Draw or Titch
From a teaching point of view, Sheet can be used in exactly the same way as Excel, Lotus 1-2-3 or Quattro Pro, with the distinct advantage that the Psion can be taken out into the field for direct data logging, and sit on a standard desk alongside a textbook and exercise book. The main subjects using Sheet would be: