Math question

Littlejen22

Drawing a picture of 2 times 8 do you draw 2 eight times? One time I saw it the opposite and was totally confused. I am pretty certain I learned 2x8 as 2 eight times. But what do kids learn now?

KTdidit

I never learned it that way, but it sounds like you are right. 2 eight times.

 

sweetwalks

Yes 8 sets of 2. So 2 eight times

Littlejen22

Well to be totally honest we were not taught to visualize math and were taught to memorize it and write it a thousand times. But I learned multiplication like counting by twos, counting by threes etc. but I recently saw it the opposite. DS' first grade math is insanely easy and he wants to learn how to multiply and I am scared to teach him differently than he will eventually learn. But since they won't even learn double digit addition for many months I guess I should not worry too much about confusing him!

sweetwalks

I was taught to memorize it to, but I've taught it by grouping.

If he's asking to learn in the first grade, teach him basics, like grouping. If it comes easy to him and he's not struggling, keep going. I think at that point it won't be confusing because he'll already grasp the concept. KWIM?

fellesferie

DS does enVision math, and his book teaches multiplication using mostly arrays and repeated addition. 

But what I found online and liked were pictures of dice. So in your example, 8 dice showing 2s. 

Littlejen22

Fells I am so sick of the dice pics, lol. That is all he is doing with addition is adding dots from dice! I hate this enVision math. But if you don't mind, can you explain what your am by arrays and repeated addition? What grade is your son in now?

Right now my son can count by 2, 3, 4, 4, and 10 so essentially he knows those times tables but does not realize it yet. So I am trying to build on that. Really I want to work on double digit addition and subtraction with regrouping but he does not so I do not want to slow him down where he is interested.

fellesferie

DS is in 3rd grade. I don't know how standard this progression is, but his school started out this year with three-digit addition & subtraction. Now they're doing multiplication/division in this order: 0/1, 2, 5, 10, 3, 4, 6, 7, 8, 9. The kids have to be solid on, for example, all 0/1 multiplication and division facts before moving on to 2s. 

In an array, they'd show the kids how 5 dots across and 3 dots down adds up to 15 dots. Or 5 + 5 + 5 = 15 is the same as 5 x 3 = 15.

I only used dice and arrays to teach him the concept of multiplication, and then we just do standard math facts. 

ETA: I HATE enVision. To the depths of my soul I hate this math book. 

Littlejen22

I am sure we will follow exactly what you guys are going since we use the same curriculm. Like I said it makes no sense for him to do this at this point he is bored and it is what he wants to learn so I won't say no. But I don't want him to have to learn a new way when he is older so I will follow their stupidity and they will waste month on a new curriculm before he is in third! Our district started with enVision Math last year.

nattyncbride

I never learned this way either, and it sounds like '2 eight times' is the majority view.

As a math nerd (undergrad in mathematics and statistics, masters in stats), when I see '2x8', I think "I have a set of 8, and I want to see it 2 times'.  Verses: "I have a set of 2, and I want to see it 8 times".

If you want 'I have a set of 2, and I want to see it 8 times', I would describe that as '8x2'.

Regardless: both are right b/c 2x8=8x2, but when explaining to a child, it might be best to be consistent between how you 'envision it' and how it's written.  I'd explain it to them the same every time, whether it's 'I have a set of <first number>, and I want to see it <second number> times' or the other way around.

Good for your son to show some mathematical curiosity at such a young age!

Littlejen22

Natty I would rather cut off my hand then take more stats classes, lol. I took two in undergrad and a few years later had to repeat it as a pre req for my MBA and I hated it so much I passed the class, got my reimbursement from work and quit school!

nattyncbride

Oh snap!  It's true that must people HATE stats.  I happen to like it.  That said, I can't write more than 4 sentences and I'm done.  So writing a 4 page paper was torture, much less a 10-15 pager. I marvel at people that read and write for a living/school/anything.  I struggle to get through long posts.  

Littlejen22

Honestly I like the idea of it and it was ok in undergrad with a calculator. But the prerequisite class made us use Excel and while I was a wiz with spreadsheets I could not do stats on it to save my life and I made the mistake of doing it as an online class instead of regular class even though I was signed as a regular brick and mortar type student. Oh well, I hated business classes anyway, lol

fellesferie

DS has been doing enVision since K. His school is very anti-text book so they follow what they call Core Standards and then use enVision (or Singapore math or fast math) to supplement whatever they see fit. 

DS has come home with a bunch of workbook pages this year that have some of the worst instructions I've ever seen. It will give a 2/3-digit addition or subtraction problem, and the instructions will say "Estimate and find the sum." It won't say how to estimate (estimate hundreds? tens?) and it won't say whether to find the sum of the original addition problem or the estimated problem or both. It will also make him draw blocks to illustrate a subtraction problem that he could do easily without it. It's just all stupid. I hate it. 

If you could show him some multiplication with money (maybe dimes and nickels?) that would help him with some stuff coming up in the book. 

Littlejen22

Funny you say use money because I tell him like pennies, dimes and dollars when talking ones, tens and hundreds places for addition and subtraction

Mkherren12

I'm a hs math teacher and I love this question!! :-) this would be a great time to talk about the symmetric property (without actually using those words of course) this property is used a lot in hs but applies here. You can do both!! 2 groups of 8 or 8 groups of 2. And show that it is the same! And any elementary teacher that grips about "doing it backwards" show be beat! (Not really) but it's frustrating when elementary teachers tell kids they are doing it wrong with the math is fundamentally right! Just cause it's not the exact same way they showed them.

+just+j+

Oh jesus.  I was taught to remember it as well.  I agree in that you could do both.

Littlejen22

Mkherren12 said:

I'm a hs math teacher and I love this question!! :-) this would be a great time to talk about the symmetric property (without actually using those words of course) this property is used a lot in hs but applies here. You can do both!! 2 groups of 8 or 8 groups of 2. And show that it is the same! And any elementary teacher that grips about "doing it backwards" show be beat! (Not really) but it's frustrating when elementary teachers tell kids they are doing it wrong with the math is fundamentally right! Just cause it's not the exact same way they showed them.

We only slowest back on Sept 9 so I don't know if this teacher is a ball buster or not but the other day he did his homework and it was a dice with 1 dot and then a dice with 7 dots and you were supposed to write 1 and 7 and then 8. He swapped the 1 and 7 and wrote 7 and then 1. I actually worried that they teacher would not mark it correct since I know they are expecting it to be written how the pictures are written. I explained to him that he did it right and the way I would count in my head with the largest number first but to make his numbers match the picture.

But I am trying hard to teah him that addition and multiplication can be reordered. And that you can check your work by doing the opposite, check addition with subtraction, etc.