Today, when I was eating, I found that my desk was square, and that desk had four corners. Dad said, "I'll give you a question to test you." If you cut off one corner of a square, how many corners are there? " I want to cut off a corner. The original corner has become two corners. Plus the original three corners, there are five corners. Dad said, "Is there any other way to cut it?" This stumped me. Is there any other way to cut it? I thought about it for a long time, but I didn't come up with it. Dad saw that I was stumped, so he said, Bring a square piece of paper and let's cut a corner to see. I brought a square piece of paper and scissors, and my father instructed me to cut them. Because of the different positions of scissors, there are three situations.

Although a corner is cut off, the cutting methods are different and the results are different. It seems that learning mathematics needs deep thinking.

2, the second grade math thesis 2

My mother is good at buying clothes. My mother bought all the clothes in my family. My father, mother and I are all well dressed. On Sunday, my mother will buy me clothes again and let me go with her.

When I arrived at the mall, I saw a pair of beautiful sports shoes. I like them very much, so I asked my mother to buy them for me. Mom looked at the style and asked if the price was 45 yuan. She thinks it's more appropriate for me to pay. I am very happy to see my mother buy me my favorite sports shoes.

After buying shoes, we went to the third floor where clothes were sold. Ah, so many clothes, all kinds of colors and brands, I'm a little at a loss. My mother asked me what kind of clothes I like. My mother and I walked and watched. I took a fancy to a white dress and tried it on. My mom says it's a little small. Let's keep choosing. Finally, my mother and I both took a fancy to a pink dress, which was just the right size. 88 yuan, the price is higher. But my mother saw that I liked it, so she discussed it with the clerk and bought it for 80 yuan.

We went shopping for a while, and my mother bought a beautiful suit for my father, 360 yuan. We left the mall.

Today, my mother spent 45+80+360=485 yuan on clothes, but she didn't buy one for herself. It was all for me and my father. Mom loves me and dad. I love my mother more.

3, the second grade math thesis 3

Many math problems are regular. Only by discovering and applying the law can we solve the problem. In today's math class, the teacher asked us to work out a math problem. The topic is this: A row of willows is planted along a road, and the distance between every two trees is 5 meters. Xiaoming ran from the first tree to the 200th tree. How many meters did he run?

At first, many of us thought it was 1000 meters, but the teacher suggested that we draw a picture ourselves. So I took out my exercise book and drew three trees on the paper. I found two gaps between three trees and three gaps between four trees. According to this reasoning, there are 200- 1 = 199 gaps between 200 trees, that is, there are 199 5 meters. So how many meters is there between the first tree and the 200th tree? Just use 199×5=995 (meters).

The answer came out and my heart was full of sweetness.

It seems that you have to think deeply and find the law to get the correct answer.