Passage From Addition Chart I to Chart II


a. Passage from Chart I to Chart II

A group of children or individual children may copy Control Chart I or the teacher may make up 36 pink rectangles which are the dimensions of the space for the combinations.

Let’s see how many combinations we can eliminate. We start from the first row 1+1=2. We must leave that…1+2=3. We can read along the diagonal the combinations that make 3. 2+1=3. We can cancel this combination. A card is placed over it, or it is crossed out. We’ll go on to the combinations that make 4. They are 1+ 3 = 4, 2+ 2 = 4 and 3 +1 = 4. We must leave the first two. But what of 3 + 1 = 4 ? This can be eliminated.

We have another chart on which all of these combinations which were crossed out. are eliminated. Something else is different. All of the combinations that make the same sum are arranged on a horizontal row. Now each column begins with a combination in which the addends are the same. But this chart contains all of the same combinations as before, just arranged slightly differently. Here you can find all of the combinations needed to do your work. The teacher gives an example or two to show that even though 8+2 is not listed, we find the sum when we look at 2+8.

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