10 frames to 20

We spent some time this week looking carefully at the numbers 11 through 20.  We have spoken about how you can tell how many groups of 10 are in a number when you look at the first numeral of a 2 digit number.  For example, 34 has 3 groups of 10, 56 has 5 groups of 10, and so on.

Now, when we look at the number 13 we can tell that there is 1 group of 10 and 3 more.  This idea is illustrated nicely when working with 10 frames.  The children worked together to figure out that they needed to fill one 10 frame to represent the 1, and then fill in 3 in the second 10 frame to represent the additional 3.

They took turns flipping over a number card, and then filling in the 10 frames.  Then they would count by ones to check their work.  Some of them realized that they could change only a few objects to make the new number.  For example, if they filled a whole ten frame and then filled 5 spaces on the second 10 frame to represent 15, when they flipped over a 12 next, they figured out that they could remove 3 objects from the second 10 frame to get to 12!