Monday, January 30, 2012

Addition: Combining Two Numbers to Find the Sum


We have been exploring the concept of addition for quite a while using a variety of approaches. We first talked about the idea of what was one more than a given number. When the children were comfortable talking about what was one more than six, one more than nine, one more than thirteen, etc., we introduced the concept of "counting on." First we compared two numbers to decide which number was more than the other one. For instance, six is more than 4, five is more than two, eight is more than three, etc. When the students were familiar with the concept of more than, we demonstrated how to add two numbers together by "counting on." When given any two numbers, always start with the highest number. Say that number, then begin to count the set for the smaller number. So, if we were to add two and four, we would begin with the four, and then count 5,6 to add on the set of two. We would not start from one, and go two, three, four, as this is a much slower approach to obtain the answer. First, we practiced with dominoes and then, dice which showed the number in dots. Later, we will practice using numbers only and no dots. Once children understand the concept of "counting on," they are well on their way to being comfortable with the concept of addition. We have also introduced the concept of subtraction using classroom and computer generated story telling.

Now in class, we are using variety of activities to reinforce the number families. We talk about all the ways to add two numbers together to make the chosen sum. If our number is "5," then we want to include 5+0, 0+5, 4+1, 1+4, 2+3, and 3+2. We talk about the combinations that are partners or related, such as 5+0 and 0+5, how they are alike and how they are different.

To insure that the children are confident using all the number activities and are familiar with adding number to make sums of 3, 4, 5, and 6, we have spent several days exploring each of these. For the next few days, the children will each select the number they want to explore. Today we played the "hand game." First we talked about how to choose a number. Did they want to pick an easier number, such as 4 or 5, or and more challenging one, like 6 or 7? Once the numbers were chosen, children worked at tables with the other children who had the same number. Each student counted out the number of pennies for their number, and demonstrated various combinations to create that sum. After a few minutes of practice using the pennies, the children were ready to record their work on the "hand game" worksheet. Each child also wrote their own number sentences using the correct number formation. On Tuesday we will continue this format using the chosen number of beads secured on a pipe cleaner to help the children to make their number families. They may stay with the same number as yesterday or choose another number from the choices of 4, 5, 6, or 7.

Later each child will be individually assessed to determine his or her understanding of addition and to decide if they are ready to go ahead with higher number families or will benefit from further review of smaller numbers.

Everyday Math is a spiraling program that revisits essential learnings until children are secure with problem solving strategies. A strong number sense of the basic facts is very beneficial for accuracy and a solid foundation for both addition and subtraction.