Chelli Posted April 24, 2012 Share Posted April 24, 2012 First off I want to state that I am not a math/science person, but an arts and humanities kind of gal. Today Chipette and I were going over her math worksheets. She had missed a couple of word problems. We come across this problem: There are 605 children at a swimming pool. There are 278 girls. How many are boys? She has the problem set up correctly to subtract to find the answer. She had missed it during her computation so we worked through it together. Me: Can you take 8 away from 5? Dd: No, so I need to take 10 from the tens, but there aren't any tens. That's the problem! Me (Miss all-I-know-is-plug-and-chug): Well, you make the zero a 9, and then add your 10 to the ones place. Dd: Why? Me: Why what? Dd: Why do you put a 9 in the tens place when there weren't any tens there? Me: (long pause) I don't know. Finish the rest of these word problems and let Mom figure it out. So I get down our set of base 10 blocks and use the blocks to work out the problem. I realized the reason you put a 9 to replace the zero is because you have to skip the tens place and move to the hundreds place. Take one of the hundreds away (or 10 tens), put 9 of the tens in the tens place, and move 1 of the tens to the ones place making the new problem: 5 hundreds, 9 tens, and 15 ones - 2 hundreds, 7 tens, and 8 ones. I was so excited that I figured out why you replace the 0 with a 9!!! I'd never thought to ask that question in all my years of ps. I just followed the formula and it works but I never thought about why :001_smile: I just wanted to share my "eureka" moment with people who would understand. And dd thought it was very funny that mom had to get out the math manipulatives to figure out a 2nd grade math problem :tongue_smilie: Quote Link to comment Share on other sites More sharing options...
blondeviolin Posted April 24, 2012 Share Posted April 24, 2012 Yay for manipulatives! :) Quote Link to comment Share on other sites More sharing options...
Snickerdoodle Posted April 24, 2012 Share Posted April 24, 2012 Yes! In your problem, there are 60 tens. When you "borrow" one of them, you are left with 59 tens. :D Quote Link to comment Share on other sites More sharing options...
Heidi Posted April 24, 2012 Share Posted April 24, 2012 Same here. Never even thought about it until I started comparing Rod & Staff (how I was taught math) to Math Mammoth (conceptual math). I've learned SO MUCH I never knew I didn't know from my daughter's 2nd grade math. :glare: Quote Link to comment Share on other sites More sharing options...
Spy Car Posted April 24, 2012 Share Posted April 24, 2012 Me: Can you take 8 away from 5? Me: Sure you can, it is -3 :D You've got to read Liping Ma's Knowing and Teaching Elementary Mathematics, you will love it. Bill Quote Link to comment Share on other sites More sharing options...
mommyto2 Posted April 24, 2012 Share Posted April 24, 2012 Congrats for your Ah ha moment! I love when that happens. And your daughter is better off seeing that when you don't know the answer to something that you take some time and figure it out. You set a good example for her future. Give your self a pat on the back! :) Quote Link to comment Share on other sites More sharing options...
Chelli Posted April 24, 2012 Author Share Posted April 24, 2012 Me: Sure you can, it is -3 :D You've got to read Liping Ma's Knowing and Teaching Elementary Mathematics, you will love it. Bill :lol: I knew somebody would call me on that. We have actually touched on negative numbers using MEP, but she knew what I meant. :001_smile: Quote Link to comment Share on other sites More sharing options...
Chelli Posted April 24, 2012 Author Share Posted April 24, 2012 The funny thing is my dh who came within a year of having an aerospace engineering degree didn't realize it either. He even took the "big boy" math classes! :) Quote Link to comment Share on other sites More sharing options...
Spy Car Posted April 24, 2012 Share Posted April 24, 2012 :lol: I knew somebody would call me on that. You had to know I would :D Snickerdoodle got lucky I didn't call her out on the "borrowing" thing, that word gets your mouth washed out with soap around here :tongue_smilie: Bill Quote Link to comment Share on other sites More sharing options...
Chelli Posted April 24, 2012 Author Share Posted April 24, 2012 You had to know I would :D Snickerdoodle got lucky I didn't call her out on the "borrowing" thing, that word gets your mouth washed out with soap around here :tongue_smilie: Bill I already knew that one! I always say regrouping. My dh and my mom look at me like :confused:, and they say, "Oh you mean borrowing/carrying." Ugh. ;) Quote Link to comment Share on other sites More sharing options...
Spy Car Posted April 24, 2012 Share Posted April 24, 2012 I already knew that one! I always say regrouping. My dh and my mom look at me like :confused:, and they say, "Oh you mean borrowing/carrying." Ugh. ;) Now that you've figured why a 9 goes in the tens place there will be no living with you :D Bill Quote Link to comment Share on other sites More sharing options...
SonshineLearner Posted April 24, 2012 Share Posted April 24, 2012 Wow.... and then we think about why we're homeschooling :) Fun to figure it out! :) Quote Link to comment Share on other sites More sharing options...
BatmansWife Posted April 24, 2012 Share Posted April 24, 2012 (edited) First off I want to state that I am not a math/science person, but an arts and humanities kind of gal. Today Chipette and I were going over her math worksheets. She had missed a couple of word problems. We come across this problem: There are 605 children at a swimming pool. There are 278 girls. How many are boys? She has the problem set up correctly to subtract to find the answer. She had missed it during her computation so we worked through it together. Me: Can you take 8 away from 5? Dd: No, so I need to take 10 from the tens, but there aren't any tens. That's the problem! Me (Miss all-I-know-is-plug-and-chug): Well, you make the zero a 9, and then add your 10 to the ones place. Dd: Why? Me: Why what? Dd: Why do you put a 9 in the tens place when there weren't any tens there? Me: (long pause) I don't know. Finish the rest of these word problems and let Mom figure it out. So I get down our set of base 10 blocks and use the blocks to work out the problem. I realized the reason you put a 9 to replace the zero is because you have to skip the tens place and move to the hundreds place. Take one of the hundreds away (or 10 tens), put 9 of the tens in the tens place, and move 1 of the tens to the ones place making the new problem: 5 hundreds, 9 tens, and 15 ones - 2 hundreds, 7 tens, and 8 ones. I was so excited that I figured out why you replace the 0 with a 9!!! I'd never thought to ask that question in all my years of ps. I just followed the formula and it works but I never thought about why :001_smile: I just wanted to share my "eureka" moment with people who would understand. And dd thought it was very funny that mom had to get out the math manipulatives to figure out a 2nd grade math problem :tongue_smilie: I have learned and awful lot, and still learning, with homeschooling. So, now....when you have a problem like this, if there is a zero there...you just immediately cross off the 60 together and make it a 59 and bring the 1 over by the 5. At least that's how I've always done it.......otherwise you have more steps if you go to the zero and nobody is home and you go to the 6 and borrow 1 and make that a 5 and bring the 1 over to the zero and make it a 10 and then you can cross the 10 off and make it a 9 and bring the 1 over to the 5......whew! Just cross of the 60 and make it a 59 and be done with it. :D ETA: Same thing if you have more 0's. Like it it were 6,005 - 278. Cross off the 600 and make it a 599 and bring the 1 over to the 5. Edited April 24, 2012 by ~AprilMay~ Quote Link to comment Share on other sites More sharing options...
mhaddon Posted April 24, 2012 Share Posted April 24, 2012 The aha moments are fun :) I am learning how to do basic addition without using my fingers. I am so proud of myself because now DH can stop making fun of me :lol: Quote Link to comment Share on other sites More sharing options...
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