Draft: this lesson was written with AI help and has not yet been read by a human editor.
1 What your class asks
This lesson asks you to read, build and take apart whole numbers up to 10 000, and to say where such numbers are used in everyday life. The museum offers one thing here, a record on how numbers are written by place value; your class brings the everyday uses and the practice. 1
Curriculum expectations, with their official codes
- B1.1 read, represent, compose, and decompose whole numbers up to and including 10 000, using appropriate tools and strategies, and describe various ways they are used in everyday life
2 The lesson
What does a digit's place tell you?
Take the same digit in the ones place and in the thousands place and compare what each is worth. Then show how a number is built from the worth of its places, and taken apart again.
Go deeper
The numerals in al-Khwarizmi's book did not begin in Baghdad. They are Indian, as their name says, and Indian reckoning had already come to Baghdad before him, in astronomy 2. TDV records that around 154 AH (770–771 CE) an Indian delegation came to Baghdad, under the caliph Abu Ja'far al-Mansur, bringing Brahmagupta's Siddhanta, or a work of the same name derived from it 2. On that book rest the Sindhind tables that al-Khwarizmi himself later made 2.
Think about it
A book came from India to Baghdad, and later a scholar in Baghdad wrote about calculating with the Indian numerals. Why is it useful to know how an idea travelled, and not only where we use it today?
Into the museum
- Algorism: how the Indian numerals and the place-value way of writing reached the Islamic world.
- al-Khwarizmi's Sindhind tables: the astronomical tables built on the Indian book.
- al-Khwarizmi: where he came from and where he worked.
Try this
Read the record Algorism. Write a four-digit number, say what each digit is worth by its place, and take the number apart into thousands, hundreds, tens and ones.
3 Check yourself
Nothing here is marked or sent anywhere. It is for you.
In your own words: what does Algorism (reckoning with Indian decimal numerals in al-Khwarizmi's book of arithmetic) have to do with this lesson?
Compare with the card
Nine numerals and a zero. The record describes reckoning with nine Indian numerals and a zero, in which each place takes its value from its position: units, then tens, then hundreds, then thousands. It adds that al-Khwarizmi wrote a book on it in Baghdad, through which the Indian numerals and the decimal system entered the Islamic world. How does a digit's place change what it is worth?
I can now