The ten times facts can form a basis for the nines and fives. Additionally, they are critical in multidigit multiplication later on.
There are a couple of tools that are useful for exploring the tens facts, but they really reinforce or explore the pattern of adding a zero when multiplying by 10.
I realized students don’t really know why we add a zero. The process looks something like this:
4 X 10 means 4 groups of 10. If we look at a place value chart: |
We place tens (or groups of ten) in the second column, which makes the number: | When we indicate the number of ones we have, we get: |
So why do we add a zero? Basically, because we have no units or singles. It’s all groups of ten.
A good visual tool is to use mini-ten frames. Students can use these to model a ten times fact and count by 10’s. | |
A hundreds board is a more abstract tool, but good for practicing the ten times facts and exploring the patterns. |
Hundreds Board | |
Mini Ten Frames (Full) |
numbers and number names: This lesson has to be extended to forty. and others like ten, twenty, thirty, forty, fifty, sixty, seventy, etc and hundred, thousand, lakh, crore, or million, billion etc whenever a new number name comes up. It is just a number name.
The experience associated with four groups of ten and four singles is different. While a number name forty is given for former, number name four is associated with the latter. No other reason can be given.
To understand what a number like thousand or lakh or crore stands for is very difficult without using digital manipulatives like videos. The concept of group of groups, group of group of groups etc is what is the experience of lakh, crore etc. i.e. (exponentiation) is the core of this. Is there a video?