Graticule slidesmicroscope slide that contains a mm grid of lines. They allow the size of objects seen under magnification to be measured. A simple version of a graticule slide can be made by anyone with access to a drawing program. Something as simple as the drawing tools that come with Microsoft Word will do (see instructions below).
Once there is a suitable grid on the computer [you could download the one to the side; see figure 1], a test print should be produced. The size of the printed square should be measured and the grid should be resized until a cm2 grid is printed. This grid can now be printed on photocopiable OHP sheets.
The OHP sheets can be glued to a glass slide with clear nail varnish.
Instructions to create a grid
Use of Word drawing tools (in italics)