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# Investigations Blog

## “Is 100 a Teen Number?” Part 2

What follows is a lightly edited version of the second part of an end-of-Kindergarten discussion about the teen numbers. In Part 1, students took up the question of whether 100 is a teen number. That conversation built on a previous one, about why there are so many 1s in the teen numbers. At a certain point in the conversation about whether 100 is a teen number, the discussion began circling around the same ideas, ones that had already been shared. At that point, the teacher made a decision to...

## “Is 100 a Teen Number?” Part 1

Not long after I witnessed a Kindergarten conversation about why there are so many 1s in the teen numbers, I visited the same classroom. This time, it was Nicole who asked a question that knocked my socks off. “I wonder if 100 is a teen number?” When I asked why she thought it might be she said, “Because it starts with a 1.” Her partner nodded, nudged her to take her turn, and they returned to their game. Several days later, I returned, for their end-of-unit discussion about the teen numbers....

## “Why are there so much 1s in these numbers?”

Last spring, I visited a Kindergarten classroom near the end of the year. Students were participating in a Math Workshop focused on the teen numbers, choosing among activities that asked them to identify and recognize teen numbers; to represent them in several different ways (e.g. on Ten Frames, with cubes, with numerals); and, ultimately, to come to see them as being composed of ten ones and some numbers of ones.  I wandered over to Stella, who was playing Race to the Top: Teen Numbers. In...