This week, Sonshine worked on subtraction within 3 digits & learning to 'borrow' from the tens & hundreds to the units.
Just for fun, i whipped out our Montessori stamp game- also to give him a visual of how this all works.
So i decide to share here, how it is done.
(Note, i am not an expert. I do this within my own understanding).
1) A green mat. On the mat, there should be 4 (here we only need 3) columns to represent the Thousand, Hundreds, Tens and Ones units.
2) A huge pool of square-shaped pieces (resembling a stamp). The stamps are divided into 3 colours, green, blue and red. Each green stamp is labelled '1', each blue is labelled '10' and the red labelled as '100'.
For simplicity, let's use the above question.
First, lay out 135 units on the mat.
Sort them in their respective column ie. put 1 Hundred (red) stamp under the hundreds column, 3 Ten (blue) stamps under the tens column and 5 one (green) stamps under the unit (ones) column.
Looking at the ones column in the question, you are asked to take 3 ones away from 5 ones.
On the green mat, take away 3 one (green) stamps.
The question also requires you to subtract 2 tens from 3 tens.
On the green mat, take 2 ten stamps away.
There's nothing to subtract under the Hundred column, so we leave it as it is.
The remaining stamps on the mat gives you the final answer.
You have left 1 Hundrend (red) stamp, 1 Ten (blue) stamp and 2 One (green) stamp, so you have your answer as 1(hundred)1(ten)2(ones); One Hundred and twelve.
I love using Montessori method to teach math because the explanation is extremely clear. And really, there is no need for lengthy explanation- you just need to demonstrate & the child WILL understand the concept.
If you think, well, Montessori is too expensive to own, well think again!
You can EASILY make your own with some creativity. I am sure you have some spare green, blue, red Legos at home, yah? Using some sticky labels, you will have your Montessori stamps in no time!
A green mat can be replaced by a green paper with lines drawn on it, yah?
Well, if you are still not feeling up to making your own...no worries.
Here's a free printable you can print from Montessori Print shop.
If you need more explanation on how to use this, you can refer here too