Dingle bell, jingle bell... It’s time for class, and we all returned to our seats. This class is my favorite mathematics, and it is geometry that I like very much in mathematics.

Before the bell ended, the teacher came in. The math teacher is very tall. Every time he walks into the class door, he will hunch his back slightly. He is usually serious in class and likes to analyze every problem in an orderly manner. His math class is like a recipe, which is appetizing to listen to and the steps are clearly explained, making people want to try it themselves after listening to it.

This class is no exception. The content of the course is one of the proof theorems of congruent triangles: if the angles on both sides are equal, the two triangles are congruent.

As I listened, I seemed to have entered the proof world of congruent triangles described by the teacher. For a while, I became one of the sides, and for a while, I became one of the corners. Suddenly, my deskmate poked me. Oh, it turns out it was the teacher who asked me the question. That question is too simple for me. But when I finished telling the answer, the whole class burst into laughter. The laughter made me stunned. Did I answer it wrong? I read the question again, yes! I looked at the teacher again, and saw that the teacher was frowning, and he didn't say anything wrong or right.

Just when I was frozen there, at a loss, the bell rang, and my classmates laughed even more unbridled. I quickly asked my deskmate: "Xiao Weng, what are you laughing at? Did I answer wrong?"

Before I could wait for my deskmate to answer, the classmates in the back row were laughing and acting in a weird accent: " A(ěi)B＝A(ěi)C...”

After hearing the tone of my classmates, I still didn’t understand what they meant. After detailed explanations from my deskmate, I learned the causes and consequences of my classmates’ laughter.

It turns out that when we usually pronounce A, we usually pronounce it in the fourth tone, but the math teacher pronounced it in the third tone that day. When I got up to answer the question, I also pronounced A completely imitating the tone of the math teacher. After hearing this, the classmates were all tickled by my funny answer, so they laughed.

In fact, with my English level, I would not pronounce A like this; with my love for the math teacher, I would not cause trouble in math class. But that day, I made a fool of myself in math class. Even though I didn't mean it, it still left a mark.

That math class was probably the most fascinating math class I listened to, and it was also the class I remembered the most, bar none.

That class and that frown are always lingering in my mind. To this day, the small rippling halo is still spreading.