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May 2012

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The ideas in this addition lesson are taken from Add & Subtract 2-B ebook. Only a few examples of each problem type are shown; you should make more problems of each kind for the student.

Carrying to tens
Free lesson plan from HomeschoolMath.net

The idea of carrying to tens (trading) should first be explained using manipulatives, or with pictures as shown below. You are adding and have so many ones that they form a new ten.  Let the student first understand the process when he does the additions with pictures or manipulatives - only after that it is time to practice adding without them.

Circle ten little cubes to show that they form one ten.  How many ones are left over? The sum goes over TEN.       tens ones   3 +     9              tens ones   5 +     8           What if we already have some tens?  Circle ten little cubes to make one whole ten.  Then count the whole tens, including the one you made by circling the little cubes. Count the ones.      tens ones 3 3 +     9                tens ones 2 5 +    8                tens ones  3 6 +   1 8                 tens ones 2 5 +   2 7           Ten little cubes (ones) form a new whole ten.

Example problem types

1.  Circle ten ones to make 1 new ten.  Mark a little '1' in ten tens column above the other numbers to signify this new ten.  Then add in the tens-column as usual, adding the little '1' also.

tens 1 ones   1 3 +  2 9        2	tens 1 ones   2 4 +  3 8
tens   ones       +	tens   ones       +

2.  Add.  If the ones go over to the next ten, mark a little '1' above the tens column.

42 +  15

27 +  45

85 +  26

83 +  15

34 +  19