抄録
In learning of mathematics, writing mathematics and speaking mathematics are very important in the process of solving the problems. Because students ought to comprehend of the learning contents through activities of writing mathematics and speaking mathematics. This study deals with the following: 1) The development of a new index to measure the change between the power of writing and the power of speaking in the process of solving the mathematics problems. 2) The relation between the power of writing and the power of speaking in the process of solving mathematics problems. We found a new index which was divided the value of the slope of a regression line by using the cumulative marks of the tests by allotment of marks of the tests. We call this new index the coefficient of variation of the cumulative marks. We experimented on the power of writing mathematics and the power of speaking mathematics for the junior high shcool students grade 2. As a result, the following became clear: 1) The value of the correlation coefficient between the marks of writing mathematics and the marks of speaking mathematics is very large. 2) Generally, the power of writing mathematics is higher than the power of speaking mathematics.
