A few days ago in math class, the teacher gave us an application problem, saying that the bird eggs in the world are ostrich eggs, and its eggs are 1300 grams. How much does the smallest egg weigh? I put a question mark in my mind. After surfing the Internet and reading books in various ways, I finally found the answer in the China Youth Encyclopedia: the smallest egg is a hummingbird egg, and the hummingbird mother lays 2~ 1 egg at a time, which is only as big as a bean, and each egg weighs 0. 5 grams, about 200 hummingbird eggs are as big as an egg. Hummingbirds can fly out of the nest for food after living for about 20 days and start an independent wild life.

What interesting knowledge, it can not only learn, but also increase extracurricular knowledge. It really kills two birds with one stone.

Math diary, a third-grade pupil, writes Fan Wener.

Once, I had nothing to do, so I took a publication from my father's desk and read it. There is a story that caught my attention: a shoe polish manufacturer asked the society for ways to increase the sales of shoe polish. He collected many methods. One person's method is very common, that is, enlarge the caliber of shoe polish. After the shoe polish manufacturer adopted this man's method, the sales of shoe polish really increased a lot. After reading it, I felt very interesting, so with the help of my mother, I did an experiment. The radius of my first shoe polish measurement was 5 mm. If 15mm shoe polish is extruded, the volume of the extruded shoe polish is 3. 1 4× 5×15 =1177.5 (cubic millimeter), which is about1cubic centimeter.

Then I increased the radius of shoe polish to 6 mm, and then I extruded the same length of shoe polish. Its volume is about 3.14× 6×15 =1695.6 (cubic millimeter), which is about 2 cubic centimeters, and it is approximately regarded as weighing 2 grams. Before increasing the caliber, according to the national population of 65.438+03 billion, 654.38+0 times a day, 654.38+0× 654.38+03 = 654.38+03 (100 million grams) was used in one day. After increasing the caliber, it used 2× 13=26 (1 100 million grams) a day, which doubled. If calculated according to the world population, it is much more. In a word, it's really small shoe polish that manufacturers can make such a big profit, the university asked!

Math diary, a third-grade pupil, writes Fan Wensan.

I saw a puzzling math problem tonight. The topic is: 37 students want to cross the river. There is an empty boat at the ferry that can only take five people. How many times must they cross the river with this boat at least? Careless people often ignore the "empty boat", that is, forget to have a gondola, so they can only take four people at a time. In this way, 37 people subtract one rowing classmate, leaving 36 students, 36 divided by 4 equals 9, and the classmate who worked as a boatman on the other side for the last time also landed 4, so it takes at least 9 trips.

Math diary, a third-grade pupil, writes Fan Wensi.

One sunny day, my parents took me to buy stationery. When I arrived at Qilu Stationery Store, I saw all kinds of book covers, including Miss Rabbit's, Pleasant Goat's and Big Big Wolf's, and Blue Bear's ... I looked at the price list: small book cover 5 yuan, big book cover 6 yuan, so I immediately took five small book covers and four big book covers. Walking, I saw a beautiful pencil case, priced at 6 yuan. Mom said, "There are several pencil cases, so I still want to buy them!" " ""just the last one! "I said imploringly." Well, just the last one! ""hmm! " Say that finish, I picked up the pencil case I picked and put it in the basket. When I got to the cashier, my father said, "Let's calculate first. How much do these cost?" I counted: "5×5+6×4+6, hmm ... 25+24+6 = 55 yuan! "Mom handed 55 yuan to the clerk, and our family went home happily.

Math diary, a third-grade pupil, writes five compositions.

In the evening, I saw a problem in the Olympiad Book: the number of apple trees in the orchard is three times that of pear trees. Master Lao Wang fertilizes 50 apple trees and 20 pear trees every day. A few days later, all the pear trees were fertilized, but the remaining 80 apple trees were not fertilized. Excuse me: How many apple trees and pear trees are there in the orchard? I am not intimidated by this question, but it can stimulate my interest. I think the apple tree is three times as big as the pear tree. If two kinds of trees are to be fertilized on the same day, Master Lao Wang will fertilize "20×3" apple trees and 20 pear trees every day. In fact, he only fertilizes 50 apple trees every day, which is 10, and the last 80 trees. Therefore, Master Lao Wang has been fertilizing for 8 days. 20 pear trees a day, 8 days is 160 pear trees. According to the first condition, there are 480 apple trees. This is to solve the problem with the idea of hypothesis, so I think the hypothesis method is really a good way to solve the problem.

Math diary, a third-grade pupil, writes Fan Wenliu.

Tonight, my mother and I played 24 o'clock and had a good time. There are many algorithms, and some have only one algorithm. For example: "3,7,8,9", its algorithm is: 3× (9-8+7). There are: 6,7, 1, 9, and its algorithm is: (9-6) × (7+ 1). There are some things that we can't figure out at 24: 1 1, 9,13,7; 8, 9, 10, 1 1, we racked our brains and couldn't figure out a way. I'll ask the teacher tomorrow! This game is full of fun and mystery.