Focus on Math

Helping children become mathematicians!

How Many More to Make 30? February 12, 2013

how many more to make 30 This is an activity I created to use with two grade 2 classes that I work with at Charlie Lake Elementary. In BC, grade two students work extensively with numbers to 100. The activity, like “How many more to make 20?” (see post from Feb. 5, 2013),  is based on one of the foundational number relationships which is, for numbers 1 to 10, anchoring each number to 10.

30 was chosen as the focal point for this activity since multiples of 10 are also important anchoring numbers.

Once again I was delighted to put some special dice to use, in this case 30-sided dice.** Each child rolled the dice and then, using a set of 10 frames, created the number rolled at the top of the sheet, right over the blank ten frames there. Thus, if 14 were rolled, the child placed a full ten frame and a one showing four on the paper, and then recorded the number 14 in the roll column of the T-chart. Then he looked to see how many would be needed to make 30, in this case 6 to fill the partial ten frame and one more full ten. 16 was  recorded beside 14 on the T-chart (see picture).

Similarly, if 7 were rolled, the child placed a ten frame showing seven on the paper, and then recorded the number 7 in the roll column of the T-chart. He could see that to make 30 he would need 3 more to fill the partial ten frame and two more full 10 frames, and thus 23 was recorded on the T-chart (see picture).

As in the “How many more to make 20?” activity, some of the children stopped making the numbers with their ten frames soon into the activity. Clearly they could imagine the anchoring relationship in their minds and did not need to manipulate the cards to “see” the numbers. Other children needed the support for every roll, but they were still able to be successful because of the scaffolding the ten frames provided.

 

I hope you will try the activity with your students!

Mathematically yours,

Carollee

Download the recording page here.

**If you do not have 30-sided dice, having students draw numbers from a bag or spinning numbers on a spinner will do nicely. You could even give students the page with the first column already filled in with numbers of your choice.

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