In this lesson students see 11–19 images displayed on fingers and 10-frames. Both representations highlight a group of 10 ones in teen numbers. Students begin to understand that each of these numbers have 10 ones and some more ones (MP7). Although some students may begin to recognize the group of 10 ones and determine how many there are by counting on from 10, this is not an expectation of students in kindergarten. Make sure that numbers 1–20 are posted in the classroom so that students can count from 1 to find the number 17 if they are unsure what the written number 17 looks like. Throughout the section, students have access to a reference sheet that shows numbers 11–20 with dots in 10-frames that they can use to identify written numbers. 

In upcoming lessons, students will compose and decompose numbers 11–19 using 10 ones and some more ones. How does the work of this lesson help build students’ understanding numbers 11–19 as 10 ones and some more ones?