1, your learning ability; 2. Teachers' teaching ability.

Generally speaking, the stronger the learning ability, the better the grades; The stronger the teacher's teaching ability, the better your grades.

Since the factor 1 remains unchanged, the fluctuation of your grades stems from factor 2.

If there is a female teacher to teach, you will be good at math; If a male teacher comes to teach, your math will drop.

By using the method of disproof, it is concluded that the teaching ability of female teachers is better than that of male teachers!