singapore math level 2 question...place-value discs

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DD is finished lIevel 1 and I'm reading through the HIG for level 2A. It recommends using place-value discs. So, my questions, did you use these instead of rods? If so, did you buy or make them?

TIA

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We used them (homemade) because they were cheaper than rods. Get the little counting disk/tokens (colored, transparent, size of a nickel) and write on them with a wet erase pen.

Other options would be rods, flats , cubes, etc but in level 3 when you get to 1,000,000 that's not practical. I have seen online rod/place value games, but again it's not practical for higher orders of magnitude.

It isn't necessary for learning to do the computations, BUT it is necessary for really getting to understand orders of magnitude. There are some fun picture books out there as well to help show what a big difference an order of magnitude makes.

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We haven't used any discs. We use rods and base ten blocks.

Rosie has videos of the concepts in SM 2, you can see her using rods and base ten sets.

http://www.educationunboxed.com/

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I wrote with a sharpie on some of those clear counter disks you can get inexpensively. We also use a base-ten set pretty frequently but for first teaching place value the discs worked better for us and it only took a few minutes to write on a sufficient number of them. I used a multi-colored set and made each kind a different color. Probably obvious but it's the kind of detail I often overlook at first!

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We use rods or base ten blocks. Or Iâ€™ve used dimes and pennies. That works only if they already understand that dimes are worth 10 and pennies are worth 1.

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For the higher-powers of base 10, I used poker chips and wrote the numbers on them with a sharpie (100, 1000, 10000, etc.). I didn't find them necessary for adding and subtracting larger numbers, but they really helped in teaching long division.

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I printed some on cardstock but we both hate them. Too thin and flat to pick up easily and they're crazy hard to sort out. So I'm very interested in what others do.

What I have done, in the meantime, is use Cuisenaire rods - separating out the ones into a baggie so we don't have to hunt for them every time.

It goes against the philosophy of Singapore, however, which uses the discs intentionally because they are identical in every respect except colour / denomination. This parallels what's known in Montessori circles as "isolation of difficulty" - you control for everything else that could be the same so the child focuses on learning what is different.

(edited to clarify: this is because a "3" looks exactly the same whether it means "3" or "30" or "300" or "3,000,000" - the only difference is in its "denomination" ie what place it's in... with rods and coins, you have many tactile differences: size, weight, material (our 100s are plastic!) confusing the issue and destroying the purity of the lesson - if you were to ask a Singapore purist, which I'm not :-))

Still - I was looking at prices on discs the other day and even though it's <\$15 at Rainbow (I think), there's still shipping costs etc that would make it rather expensive for something we use for 3 minutes at the start of a lesson.

Following to see what others have done!

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I used place value rods.

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I have square centimeter cubes and went on to make my own base ten rods and then hundred flats - we are also about to start Singapore 2A. After that I think I will tell my DD that 1000 is the number of centimeter cubes we had when we first bought them and leave it at that - 2000 would have to be 2 tubs worth of cubes - I think after that she should have the idea that things get big pretty fast.

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No we do not use them. I use C-rods and base ten blocks. ;)

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2000 would have to be 2 tubs worth of cubes - I think after that she should have the idea that things get big pretty fast.

Well, in fairness, the idea isn't to teach kids that "things get big" but to have them be comfortable working with (manipulating!) them as concrete reinforcement. (I'd rather use BOOKS to teach about things getting big, like Steven Kellogg's How Much is a Million, The Cat in Numberland and Anno's Mysterious Multiplying Jar.)

I do realize that concrete reinforcement is downplayed in Singapore more than in other programs we've used, but still... if you're just TELLING them it's a lot of cubes, I don't think that's the same, sensorily, as holding them. And as others have pointed out, base-10 materials, rods, etc., get really unwieldy after 1000s.

Whereas chips are chips, and the value is just whatever you say it is. So they are stronger in one area (abstraction of place value) but weaker in another (concretization of place value).

We have big plastic 100s, and I stack all ten up to show 1000, but showing and knowing isn't enough if can't actually work with the materials. I suspect I will have to improvise something chip-like once we head into 3A, where the numbers do get bigger.

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Yes, beyond about the 100s it does get too inconvenient to work with manipulatives like that - but to be honest by working with money they have already got the idea that a small thing can represent a much larger value. (Where I live while the notes are slightly longer at larger values, it is not very noticeable and my DD is quite aware of the value - so using poker chips will not present any problem for her)

Having not get yet to those very large numbers I have not considered yet what I will do for manipulatives, but really the concept is the same - if they are getting it in the tens then the hundreds should be easy and the thousands and so on should be just as easy - explaining what the numbers mean and the actual quantities involved is far more tricky than being able to manipulate the numbers - I do like the books you mentioned for doing this though.

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We bought a pretty inexpensive set of foam discs in our local ed supply store. Big numbers are not cumbersome at all, because the essential idea is redistributing tens.

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Thanks for all the replies...I think I'll go with the chips...I assume I can get a cheap set at walmart. If it's something useful in the upper grades than it's worth it for me. I'll have to check out Rosie's video's and see what she does with the rods!

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