MathBlackBoard is a Java program that has unique GUI (Graphical User Interface). By using GUI, MathBlackBoard users can input, edit and manipulate mathematical expressions easily. And MathBlackBoard has its own kernel. However, it has functions to use other computer algebra system as computational engine.
In this paper, we describe an example of using MathBlackBoard. We have added a new function which is designed to be used in junior high school classroom. And we have used it in classrooms.