Abstract
The emergence of tablet devices such as the iPad has created a new task for software development. To develop a new version of Geometric Constructor (one of the dynamic geometry software) solving this problem, I made four requirements; (1) that it is a software which is used in multi-devices such as PC, iPad, Android tablets, (2) that it can be used as a web application on-line and that it can be used as a stand alone application off-line, (3) that it can be used with multi-touch interface to investigate figures mathematically, and (4) that it contains almost all features of GC/Win. In order to meet these requirements, the new version of GC (GC/html5) was developed based upon HTML5 and JavaScript. Development of GC/html5 and its use in many lessons shows that it meets these four requirements. From this, we can infer that (1) we can develop educational software like GC/html5 (which is over 400kb in size), which can be used with multi-devices, based upon HTML5 and JavaScript, and (2) the concept of combined file is important in order to clear the requirement of on-line and off-line use.
