P2 Math - General Discussion

[jedamum]

without looking at the answer, i guess 210; ds1 said 30.

the answer 30 is correct. those who has My Pals are Here textbook, pls refer to pg 10; the ‘working’ is there. so if the kids are taught like that in sch, they will probably get it correct.

[corneyAmber]

Gosh…gotta check textbook later. Thanks way2go, blobbi, king, sunflower n jedamum!!! I seem to learn sth new each day on conventions.


But why are we splitting hair on concepts with connected boxes and separated boxes convention?

My simple mind tells me the following based on concepts:

tens-----ones
5---------6

means:
50 + 6 = 56. If based on model ans, means half tens, =>5+6=11??

[metz]

It’s considered as bars of tens in the Tens columns. Therefore, in the above pic, it simply implies 2 bars of tens = 2 tens = 20.


The use of bars of tens in the Tens columns seems to be a standard practice. And that goes for hundreds too. Usually, a 10x10 block will be used to represent 100. So, 2 10X10 blocks = 200.

So far, I have yet to come across questions that put single blocks in the Tens/Hundreds columns.

[buds]

I agree with chamonix on this. The application of operations

using such materials be it cubes or beads simply implies what
it really is... visually.

Montessorian children are guided on systematic steps; on how
they should work with the Golden Beads during the early stages
of learning math operations in the Montessori Math curriculum.

The calculation of units are only up to 9 units or 9 ones. Each time
the units total up to ten units, children are to exchange with the
bank (teacher), for a ten bar..

They are also taught to count in tens....
> 1 ten bar is also 10.
> 2 ten bars is also 20.
> 3 ten bars is also 30.... and so on.

They get to work with the bars on their own,
with the teacher and also in groups as revision
games. Children take turns to arrange the number
of ten bars and the rest in the group must tell the
answer. Children also get to match number cards
corresponding to the beads shown on their work
mats.

In the case of this question... should they work with
number cards, the cards they would take would be
20 and 10. The cards cannot be read as 20 and 10.

In this case, where the eventual value is asked of the diagram, i
find there is no ambiguity of any kind. It is kinda straightforward.

a. 210 does not justify the 2 tens in actual fact. Unless if it is phrased
as 2 tens or 2 10's and provided the answer (30) isn't one of the MCQ
answers.

b. 210 cannot be the eventual answer as the diagram cannot be read
as 2 ten 1 ten or twenty and ten.

c. 210 cannot be the eventual answer since as both my DDs said..
:slapshead: that number is read as two hundred and ten, not 2 ten.

Just sharing.

[corneyAmber]

Thanks chamonix n buds, I can see the convention now, in fact all of you explain very well so I can get the idea even before checking textbook.


Using the same approach or convention,here is another question.

How many tens are there in 751?

[sleepy]

ksi:

Which would you choose?
1. 20
2. 29
3. 30
4. 210

Is this question considered tricky or ambiguous??? :?

My dd's answer is 3
2 tens and 10 ones

ksi:

How many tens are there in 751?

My dd's answer is 75

[metz]

ksi:

Using the same approach or convention,here is another question.

How many tens are there in 751?

It all depends on the context of the question.

If the question is a standalone question, 75 tens should be the acceptable answer.

But if the question is phrased as such - ___ hundreds, ___ tens, ___ units

then I believe the appropriate answer should be 5 tens.

[sunflower]

chamonix:

ksi:

Using the same approach or convention,here is another question.

How many tens are there in 751?

It all depends on the context of the question.

If the question is a standalone question, 75 tens should be the acceptable answer.

But if the question is phrased as such - ___ hundreds, ___ tens, ___ units

then I believe the appropriate answer should be 5 tens.

Agree! :celebrate:

[UmmuMuadz]

Hi,


I was going through DS1’s Maths Textbook yesterday.. He’s in Primary 1.

Under the topic addition / subtraction within 20, the method is follows:

12 + 3 = ___

First, break the 12 into 10 + 2

Second, take 2 + 3 = 5

Lastly, the to get the answer, you take 10 + 5 = 15

This is the method he was taught in school. This is the first time I come across such method. :shock:

When asked whether he understands this method, he said no. Instead, he is using the old school method of putting 12 (in the head) and calculate using the 3 fingers to add on.

I would like to ask if the textbook method better in terms of making the child understand the concept as compared to the old school method?? :?

Thx

[corneyAmber]

This new method uses the strength of number bond for 10s to help the children calculate faster.


Using fingers for calculation has its limitations so it is not encouraged as numbers get bigger.

Abacus method also uses number bonds of 5 and 10 to calculate big numbers.