Discussion in 'Elementary Education Archives' started by zoedoe, Mar 29, 2005.

1. ### zoedoeRookie

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Mar 29, 2005

I am student teaching in a second grade classroom. I have to teach my students how to add with double digits and I have no idea how to do this. The math book that my CT gave me is useless. I really need help with this.

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Mar 29, 2005

52
+24
____
70 (50+20)
6 (2+4)
________
76

Last edited: Mar 29, 2005
4. ### ViolaSwampHabitué

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Mar 29, 2005

If you have base ten blocks it is a snap. You will only need the ones cubes and the tens sticks. Send out an e-mail to the school if your CT doesn't have them. I guess you could use sugar cubes and a photocopy of 9 stacks (lines) of 10 cubes in a pinch.

This is a rough explanation. Hopefully you'll get the idea. You talk about the tens place and the ones place. You talk about how it takes 10 of the small cubes to make a ten stick. Teach them to always have less than 10 cubes otherwise they must trade up and replace with a tens stick. Then they simply count the number of tens and count the number of ones and that is their answer. Pretend each line of zeros under my "Tens" heading is a tens stick and each individual zero under the "ones" head is a single ones cube. Please ignore the lines in between my columns. I Had to get creative to separate the two columns. For some reason it wouldn't accept the blank spaces.

Tens|Ones
0 0 |
0 0 |
0 0 |
0 0 |
0 0 |
0 0 |
0 0 | 0
0 0 | 0
0 0 | 0
0 0 |

Count the number of each kind. I have 2 tens and 3 ones. My total is 23. From here you just walk through adding two different numbers together, always making sure your ones are less than 10 or you trade up. Also make sure you chose two numbers that add up to less than one hundred, you don't want to make the mistake of teaching them 3 digit addition and not introducing them to the 100s place value.

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Mar 29, 2005

if the school doesnt have base ten, she could use skittles, smarties or m and m's as units and pretzel sticks as tens!

6. ### bernburnRookie

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Mar 29, 2005

Every student should have a number line on their desk to help with adding and then carrying numbers to the tens column

7. ### StillaStudentNew Member

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Mar 29, 2005

Hi ZoeDoe...

I am still a teacher in training
I will be starting my student teaching in about a year...

But I think I have a really good way to show you how to do double (even more) digit addition.... just learned this in my teaching elem. math class.

Not sure if it will post the way it needs to but we'll see....
If you have any questions just msg back. I think this is an AWESOME way to get the students to start thinking of how this works (as well as the method that love labs posted)

k.. here it is..

6 7
+4 5
______
|1 /| 1/|
|/ 0 | /2|

1 1 2

Basically you make a box underneath the problem and then draw a line between where each number in the problem is.... next you make the diagonals.
Now we have under 7+5 = 12
and we have under 6+4 = 10
Then you have to add across the diagonals....
so there's 1 then 1+0 then 2
Under each diagonal box you write the total that was in that diagonal.

It's real simple and easy to understand (but hard to explain over the computer... )

Good luck with your student teaching!!!!
~Becki

Last edited: Mar 29, 2005
8. ### bam451Rookie

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Mar 29, 2005

I discovered something this year that really worked with double digit addition with regrouping. Let's say the number is 55+5. I tell the students to cover up the tens column. Then we add 5+5. I tell the students that there is only room to put one number in the ones column. When they tell me that 5+5=10, they put the 0 in the ones column and then we carry the one and put it above the tens column. But when we carry the ten, we all reach to the ground and pretend that we are lifting the one and putting it above the 10's column. The kids really got a kick out of it and it really helped. I hope this helps!!

9. ### czaczaMultitudinous

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Mar 29, 2005

I have to go with Bam's idea and the manipulatives- these are most 'real-life' and tied to what the concept truly is....Tens blocks are awesome. I've seen people make them with beans- just single beans for the ones and ten beans glued to a popsicle stick for the tens. I like the idea of saying there is only room to put one number in the ones column. If they TRULY understand place value they should know that 10 for instance is 0 ones and 1 ten- so the zero stays in the answer in the ones place and the 1 gets added to the tens.

10. ### DoublescoopCompanion

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Mar 31, 2005

I found an incredibly motivating way to teach both 2-digit addition and subtraction. I tell the kids that we're going to have a party with another class but that we have limited supplies. We then figure out from a table of classes in the school how many ppl would attend our party if we invited each class (i.e. our class 23 and their class 27 = 50 kids). When it came to subtraction, I created a table of the ages of all the teachers. (I posted a list in the staff room and said teachers could tell their real or imagined ages. lol) We then figured out how much older this teacher was than that and how much older each teacher was than the kids. They loved it!

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