# Focus on Math

## Helping children become mathematicians!

### How many more to make 20? February 5, 2013

This is an activity I created to use in a grade one classroom here my school district. (In BC grade one students work extensively with numbers to 20.) It is based on one of the foundational number relationships for numbers 1 to 10: anchoring each number to 10. A set of ten frames is a fabulous tool to help build this relational understanding with young children. The ten frames provide a visual representation of each number and clearly show how far away each number is from 10.

Along with 10 being an anchoring number, multiples of 10 are also important
anchors. With this in mind, I felt it was important to give grade one children the opportunity to practice anchoring numbers to 20.

I had some 20-sided dice that were perfect for the activity**. Each child rolled a die 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 20, in this case 6, and recorded it beside 14 on the T-chart.

Similarly, if 7 were rolled, the child placed a partially filled 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 20 he would need 3 more to fill the partial ten frame as well as a full ten more, and thus recorded 13 on the T-chart.

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

**If you do not have 20-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.

### 2 Responses to “How many more to make 20?”

1. Yes, Carolyn, it ties into whole-part-part, and then the anchoring and the visual component, it builds understanding in three of the “big four” number relationships for little people. (See “Big Ideas for Little People” blog post for more about those four relationships.)

2. Carolyn Gray Says:

Looking forward to using this, great idea goes great with part part whole, thank you. C

On Tue, Feb 5, 2013 at 3:30 PM, Focus on Math