## Singapore 3B, Specific Lessons

cbollin

### Singapore 3B, Specific Lessons

Measurement
ChristyH wrote:My dd who is 11 and in 3B is struggling with gals, pts, and qts. addition and subtraction. I generally break these problems down to the lowest part and then subtract and then divide back up to whatever is asked for. This seems like the long way around for these answers and since they give you no room to write I am wondering if these are suppose to be done mentally. Any suggestions?
The US measurements is not a thing to get bogged down on. You'll move on soon.

In 3B with the gallons, pints, and other US measurement we write it down on dry erase board if needed. I even have a hard time doing that in my head when I am cooking, so I don't care if my kids have to write it down to see it. It's a lot to track.
Typically my 10 y.o will do that along the lines of regrouping:

2 pints 1 cup
minus 2 cups

gets changed along the same lines of thinking of a subtraction problem of 21 - 2. it becomes "ten & 11" minus 2.

except that US measurements are not in groups of tens, which makes it rough to think mentally about. So, if they can't do it mentally, it's ok in my book. We use Pints and Cups as our place value grouping in the problem. (or as my dh likes to confuse me once in a while.... wow! you mean you're introducing math in things like base 16 (ounces to cup) and base 3 (cups to pints?) Don't make it mental math requirement right now for that, ok? thank you honey.)

so it is converted along the idea of basic grouping:
1 pint 3 cups (this is the same as 2 pt 1 cup, right? just like 21 is ten plus eleven when regroup)
minus 2 cups
equals
1 pint 1 cup.

sometimes we've practiced it as
2 pt 1 c
- 2 cu
equals

4 plus 1 cup, 5 cups
- 2 cups
equals 3 cups which is 1 pint 1 cup.

but that seems harder to my child. I don't know why yet. But she prefers to do it the stack it method. so I'm ok.

Yes, I can do it mentally, but I don't have the expectation that my elementary child HAS to do it mentally right now in3B or even at the stove when it really counts. Just like any other mental math in Singapore, we write down what we did to lock it in our brains, talk through the problem out loud for the process. write down and go longer if needed.

Find bottles and jugs around the house to use to help cement the amounts and all of that. We have measuring cups, drink bottles, milk jugs, etc. let them fill up the containers and look for those "skip's by 2's"

-crystal
Julie in MN
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Joined: Mon Jun 28, 2004 3:44 pm
Location: Minnesota

### Re: Measurement

cbollin wrote: I don't care if my kids have to write it down to see it. It's a lot to track.
I did that, too. Provided a "cheat sheet" printout of conversions.

I'd see if that solves the problem before I'd worry about his not understanding how to do the math.

We also did a lot of pouring of water in either 2B or 3B (or both). It made the lesson more fun
Julie, married 29 yrs, finding our way without Shane
(http://www.CaringBridge.org/visit/ShaneHansell)
Reid (21) college student; used MFW 3rd-12th grades (2004-2014)
Alexandra (29) mother; hs from 10th grade (2002+)
Travis (32) engineer; never hs
cbollin

### Singapore 3B - Exercise 35 Question...

LA in Baltimore wrote:Hi Everyone!
We were working on Exercise 35 #2a in the student workbook this morning.
I either made the problem way too hard or it is not the best choice of denominators for a beginner!
We needed to put three fractions in order, beginning with the smallest.

We solved it by making the denominators the same so we could easily compare the fractions.
The only problem with this was that 30 was the least common denominator!
2/5 became 12/30
1/2 became 15/30
and
5/6 became 25/30.
Was there a simpler way to do this?
#2b-d were much easier since the common multiple was always one of the fractions already given. #2a just seems out of place.
That's what we did too. it has to be denom of 30. It didn't seem that out of place to us, but it did require an extra moment of hand holding for my average child.

The first thing I did was to have her change the 1/2 to 3/6. Now we have just two denominators of 5 and 6. But they are not "skip counts of each other". They got one practice problem on it in the textbook (p. 74 10 c) with 3/5 and 4/7 before doing the worksheet and that's where we worked on it.

-crystal
Julie in MN
Posts: 2909
Joined: Mon Jun 28, 2004 3:44 pm
Location: Minnesota

### Re: Singapore 3B - Exercise 35 Question...

When we were doing Singapore 3 & 4, I felt there was a "challenge" problem every so often. I didn't feel that way in 5 & 6.

The next step in fractions is to realize you may be multiplying the denominators together -- which would be 5 and 6 and 2. Since 2 is already "in" 6, you don't have to multiply that.

Not having that book here any more, that would be my guess -- it's throwing it out there for the kid who may be ready to discover the next step, like your first child probably was. My *youngest* did Singapore & was never interested in discovering the next step, either :o)
Julie, married 29 yrs, finding our way without Shane
(http://www.CaringBridge.org/visit/ShaneHansell)
Reid (21) college student; used MFW 3rd-12th grades (2004-2014)
Alexandra (29) mother; hs from 10th grade (2002+)
Travis (32) engineer; never hs
Julie in MN
Posts: 2909
Joined: Mon Jun 28, 2004 3:44 pm
Location: Minnesota

### Metric Scale (lesson in Singapore 3B)?

TriciaMR wrote:I noticed in the LP for Singapore 3B that we need a metric scale to measure some things. Ummm, my digital scale only measures in pounds. I have a kitchen scale that does oz or grams, but I don't think it can handle a backpack with books. My dd said, "Maybe we could just go to the grocery store and do school in the produce section?"

I get the idea of the lesson is to guestimate weight, and then measure how much it really weighs, so we could just pick lighter things, but I was just wondering what others did.

=Trish
Is it possible to just do the exercise using USA weights & measures?

Otherwise, you might check your bathroom scale. Ours can be changed to kg. somewhere on the back (dh has to do that for medical records) and others have a number wheel with kg. showing in smaller print.

Julie
Julie, married 29 yrs, finding our way without Shane
(http://www.CaringBridge.org/visit/ShaneHansell)
Reid (21) college student; used MFW 3rd-12th grades (2004-2014)
Alexandra (29) mother; hs from 10th grade (2002+)
Travis (32) engineer; never hs
cbollin

### Re: Metric Scale (lesson in Singapore 3B)?

Are you talking about p. 31in workbook? It looks like we subbed in a bag of coffee (which had the weight in oz and grams), bag of flour.

then, we learned our own weights in pounds and converted it. Did it and moved along.

use bathroom scale and maybe convert it if you don't have Kg. (you could do that manually or use
http://www.metric-conversions.org/weigh ... ograms.htm
you could go to a place with a metric scale

-crystal
dhudson
Posts: 320
Joined: Thu May 10, 2007 5:46 pm

### Re: Metric Scale (lesson in Singapore 3B)?

We used a digital bathroom scale that converted to metrics. I would just use the kitchen scale and measure lighter things.
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