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I just use a calculator.


They were teaching this, rounding, and lattice math to my child. Instead, my wife and I taught them rack and stack and she killed it on the NWEA.

Something similar was happeinging with multiplication and division, but the new method did a better job of teaching principles of what youare doing when you multiply and divide. However, to make our kid actually good at multiplication and division we have been simply pounding the tables into her head via repetition and memorization.

Again, she is scoring way better now on the NWEA tests.

At true high level you do this:

26 is approximately 30
17 is approximately 20.

Answer is 50; say the order of magnitude is right and within acceptable error.

What, Do kids just not cheat off the asian kid anymore?
Am I the only one who misses the old way?

The initial picture confused the hell out of me. Having read the discussion in the tread I can see what they are doing. It is not the way I would elect to teach maths and if my (future) children are taught this method I will try to teach them the same way, unless they really don't get it then I will teach them to break the nunbers into tens and units and adding in blocks.

"Thankfully" most of the maths I do now is pretty much just throwing random letters and punctuation around a page/computer program, so I don't actually have to add up numbers very often

Well, if all else fails just go to the source:

Basically this particular way to teach math only deals with the first grade and it is designed to:

a) teach kids that there are tens and ones
b) that 10 ones make a "ten"
c) when you add or subtract single digits, sometimes you have to create or take away a "ten".

From the actual guidelines for the standards:

In first grade, students learn to view ten ones as a unit called a ten.
The ability to compose and decompose this unit flexibly and to view
the numbers 11 to 19 as composed of one ten and some ones allows
development of efficient, general base-ten methods for addition and
subtraction. Students see a two-digit numeral as representing some
tens and they add and subtract using this understanding.

And the actual standard (with the relevant portion causing the question in the OP in red):

1.NBT.4: Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used. Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.

Here is the actual example picture for the method questioned by OP:



All it does is reinforce to a 1st grader that "You have 4 tens and 3 tens, that gives you 7 tens. You have 6 ones and 7 ones: 6 ones and 4 ones make a new ten. Combine that new ten with the 7, and then you have 3 more ones. 4 tens + 3 tens + 1 new ten + 3 ones makes 83."

This is not to teach them a strategy that they will use to add and subtract for the rest of their lives. All this does is teach a 6 year old that "when you add enough ones, you make a new ten. And if you take away enough ones, you take away a ten."

Want to know what horrible new-age strategy they are using to teach these kids addition by 2nd grade:



By 2nd grade the kids have mastered the concept of "enough ones make a new ten" and don't have to write it out anymore. Now they learned to take the newly constructed ten (aka: carry the one) and add it to all the other tens. They also learn that enough tens make a new hundred and to use the same strategy there.

So the picture in the OP is not a new way to teach how to add. It's just a new intermediary to make sure that kids understand how "30something and 40something can equal 80something instead of 70something. Because even though 3+4=7 you might end up with enough ones to make a new ten".

Who knows, maybe CommonCore is not the great Satan after all...

 AlmightyWalrus wrote:

 d-usa wrote:
The old way often involved not actually learning how to do sums, or any math for that matter, It's just memorizing tables. Kids know the answers because they have repeated them often enough, but they might not know why that is the answer.

Coming up with ways to teach stuff that actually lets kids understand and do the steps in their heads is always a positive. That's the best way to learn: don't teach them the answers, teach them how to find the answers. And base 10 is a good way of doing that, i play Warmahordes and when I roll 5 D6 I basically do exactly this.

Exalted. Understanding is the true goal of education after all.

I don't know what "old way" you're speaking of. I was definitely taught HOW to add (there were no addition tables). I was taught HOW to multiply before being told to memorize the tables for ease and speed. Granted this was 30 some odd years ago, so there may be newer "old ways" since then.

I was taught to memorize tables and only really actually knew why I was doing what I was doing in late elementary or early middle school. At first I was going to complain about the math in the OP but this morning at quarter to seven I sat down and thought about it before going to university and looked it over in the half light of early morning and it actually made sense to me. Its essentially trying to explain something that most of us do in our heads, round to the nearest ten and add whats left over.

 Daba wrote:
At true high level you do this:

26 is approximately 30
17 is approximately 20.

Answer is 50; say the order of magnitude is right and within acceptable error.

Good enough for government work

 Dreadclaw69 wrote:

 Daba wrote:
At true high level you do this:

26 is approximately 30
17 is approximately 20.

Answer is 50; say the order of magnitude is right and within acceptable error.

Good enough for government work

Wouldn't 26 is approximately 25 and 17 is approximately 15 make more sense? You'll get 40, that's a smaller margin of error. Can anyone do multiplication and division with large numbers rapidly? I mean things like 326 x 185, not simple 15 x 15.

 trexmeyer wrote:
Wouldn't 26 is approximately 25 and 17 is approximately 15 make more sense? You'll get 40, that's a smaller margin of error. Can anyone do multiplication and division with large numbers rapidly? I mean things like 326 x 185, not simple 15 x 15.

Why round to 5 when you can round to 10?

For 326 x 185

Approx to 300 x 200 = 60,000 or 6 x 10^4

Order of magnitude is ok, so it seems legit.

So:

26+17
Take 3 from the 26 and drop it on the 17 to make 20.
Making 23+20, or 20+20+3. Easy

Or, 25 and a bit + 15 and a bit.
25+15 = 20+10+10 = 2+1+1 with a 0.
And a bit.