Tag Archives: teaching children

Degrees and angles | 角度

Today in the fourth grade weekend lesson we learned about angles📐 and degrees. We explained what degrees was first🥇 because angles are classified using degrees📏. Degrees were discovered by Egyptians. They invented the degree symbol ° and also came up with the 360° circle⚪.  There is an interesting history of how they connect the movement of the Sun with time.   They first divided a year into 360 days, noting that the Sun moved in a circle. Around 1500 BC Egyptians divided 24 hours⏳, though the hours varied with the seasons originally. Then the Greek astronomers made the hours equal. About 300 to 100 BC the Babylonians subdivided the hour into base-60 factions: 60 minutes an hour and 60 seconds in a minute.

We use degrees to measure angles. An angle is a figure formed by two rays🛴 called sides of the angle. In geometry there are three types of angles: an acute angle between 0 and 90 degrees, right angle a 90 degree angle, and an obtuse angle between 90 and 180 degrees. In 1936 a clay tablet was found buried at Shush (Khuzestan region of Iran🌏) some 350km from the ancient city of Babylon on which was inscribed a script that was only translated as late as 1950. The text provided confirmation that the Babylonians measured angles using the figure of 360 to form a circle. The Babylonians knew that the perimeter of a hexagon was exactly equal to six times the radius of a circumscribed circle. This is why they chose to divide a circle in 360 parts⚪. If we did not discover degrees or angles we would not be able to build anything properly🧱. So if we tried building a house without degrees or angles the house would collapse🏚.

We will talk about triangles next time.

Welcome to our New Google Classroom!!😃

Hello everybody!😃 Welcome back to Magic Math Mandarin.  Since we are staying home because of covid-19, we brought our classes to google classroom so our students can keep on learning even during this pandemic👩‍🏫. Now we can all communicate with each other online💻. In this classroom we will be learning Chinese🈷, math➗, and programming👩‍💻. Our teachers will put new assignments everyday about each topic.  If you would also like to join our wonderful classrooms then here is the class code mtxl6j4

Remember to stay home and don’t get sick!😷 Please join our classroom today!👍💖


python numpy basics | 基础 python numpy 1

Tonight our class played together numpy basics and math.  We put together a numpy basics notebook:

Programming by trial and error is a great way for kids to learn not only programming but also math. — this should play a bigger and bigger role in children’s day to day learning.  玩编程也帮助学习算术。

Somehow I have a feeling that learning long division in this day and age is wrong.  在这个时代还学长除法那就不对了。

Go ahead and tinker with the code in the notebook. Nothing will break, we promise 🙂

To see a world in a grain of sand | 从沙粒看世界

Professor ShouCheng Zhang “passed away”. He is forever with us, seeing a world in a grain of sand, holding infinity in

这是张首晟所有视频里我们最喜欢的一个视频。 张教授深入浅出,循循善诱。尽管已经“离世”, 张教授永远和我们在一起从沙粒看世界,把永恒留在刹那时光。

We won’t quote any physics or mathematics from the video, except the title of the lecture, originally from William
Blake, and dedicate them to Professor Zhang:

To see a world in a grain of sand
And a heaven in a wild flower,
Hold infinity in the palm of your hand
And eternity in an hour.


Chinese style education & empty basketball courts |中国式教育和空荡荡的蓝球场

I was in China this November to conduct surveys on education.  I had a few chances of sitting in some after school education programs and cram school classes, including XDF新东方, and was shocked by the amount of work Chinese kids have to do and was saddened by the way they are learning.

Let’s talk about the amount of work first.   I saw very few kids out and about any time of day except commuting hours.   Basketball courts are empty, even on weekends.   Where are all the kids?  They are in endless cram school 补习班 classes.

A middle school child routinely gets up before 7 am and does not go to sleep until midnight or after.   Middle school students stay in school until 8 pm, and work on additional homework from 8 pm till midnight.   Younger students are often working similar hours.

Teaching long division |长除法

Long division is still taught exactly the same way many years ago: a highly mechanical process that is worse than doing dishes.

Perfecting the steps is essentially the same as robot training.

Our classes should discuss why long division was invented and why it works, and why there are many other ways.


人之初 性本善 性相近 习相远

苟不教 性乃迁 教之道 贵以专

养不教 父之过 教不严 师之惰(duò)

子不学 非所宜 幼不学 老何为

Brenda Barnes’s advice to her children

Every advice in this list is important and should be read them often.

1.  Work hard and do good work.
2. Value family. They will always be there for you. You may have tiffs, but work at keeping a healthy relationship.

Financial math equations

  1. Revenue – Expense = Profit,
  2. Net worth= Asset – Liability

My dear children learned while we were shopping at IKEA that:

Revenue & Expense by Elizabeth
Revenue & Expense by Elizabeth

  revenue = money coming in  expense = money going out

  profit = revenue expense

Money that mommy earns from her work is revenue

Apartment rental income is revenue

Money we spent paying for everything we use is expense

  asset = things that bring in profit

  liability= things that do not bring in profit

Can you please tell me what are the assets and what are the liabilities that you know?

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