Introduction

For the final answer, restricted unit requires the student to convert/rescale answers which are likely to be messed up. Though most questions have obvious answer unit, but it is not the case that question have quantities over few order of magnitudes. The free form input is also essential part to test the knowledge of the student to handle physical quantity.

Idea

To get the idea of how the unit conversion system work, the most easy way is to try it yourself. You can download an independent program unit_convert.php (put together in the coordinates package) which give a more visual presentation of the unit system. Here are some screenshots:

TODO: documentation added later