Students answer “how many?” questions and count out groups within 20. They understand that numbers 11 to 19 are composed of 10 ones and 1, 2, 3, 4, 5, 6, 7, 8, or 9 ones. They write numbers within 20.
Unit Narrative
In this unit, students count and represent collections of objects and images within 20. They apply previously developed counting concepts, such as one-to-one correspondence, keeping track of what has been counted, and conservation of numbers, to larger numbers.
Previously, students counted, composed, and decomposed numbers up to 10. They used counters, connecting cubes, 5-frames, 10-frames, drawings, their fingers, and other tools. They also wrote expressions to record compositions and decompositions.
Here, students use the 10-frame to organize groups of 11–19 objects and images. This tool encourages students to see teen numbers as 10 and some more, emphasizing the structure of the numbers 11–19. Students use this structure as they represent teen numbers with their fingers, objects, drawings, expressions, and equations. Students see equations with the addends written first, such as . It is important to note that students are not expected to think of 10 ones as a unit called “a ten” or refer to single units as "ones" until Grade 1.
Throughout the unit, students practice tracing and writing numbers 11–20. It is common for students at this stage to write numbers backwards, so the emphasis is on writing a number that is recognizable to others. Reversing the order of the digits of teen numbers is also expected, due to how teen numbers are said in English. Repeatedly seeing the number 1 written first to represent teen numbers helps students recognize the structure of these numbers.
When tracing and writing numbers, students should write on a flat surface while sitting in a chair with feet flat on the floor. Number writing practice can also happen in other parts of the day and can be done using a variety of writing tools (crayons, colored pencils, markers, and so on) for increased engagement. Students can practice creating numbers with dough, tracing numbers in sand, or forming numbers with pipe cleaners.
Understand numbers 11‒19 as 10 ones and some more ones.
Section Narrative
In this section, students see the numbers 11–19 as 10 ones and some more ones. They compose and decompose teen numbers and record the compositions and decompositions with objects, drawings, and expressions.
Students use fingers and 10-frames to represent these numbers, but there is more emphasis on using the 10-frames as the lessons progress. To represent a teen number, students fill a 10-frame and show some more ones, which they may arrange in different ways. To determine the number of objects, students may count all or count on from 10 (though the latter is not an expectation in kindergarten).
Students compose and decompose teen numbers by starting with the parts (“10 and 5 is 15”) and starting with the total (“15 is 10 and 5”). For the first time, students see equations with the addends on the left side of the equal sign (). They complete equations that show unknown parts or an unknown total to represent teen numbers as 10 ones and some more ones ( and ).
Starting from this section, students have access to a reference sheet that shows numbers 11–20 with dots in 10-frames, which they can use to identify written numbers. Students can count the dots to determine which written number is on the card.
In this section, students count groups of 11–20 objects using strategies they developed earlier when working with smaller sets of objects.
Students participate in the Counting Collections center as the first activity in each lesson. They think about how organizing the objects can help ensure an accurate count and use organizing tools, such as counting mats and 10-frames. Students also recognize that the number of objects in a group does not change, regardless of the way the objects are arranged.
Display written numbers for students whenever they share their count. Students practice tracing numbers 11–20 in this section, but they are not expected to write the numbers. In later sections, after seeing the numbers displayed repeatedly, students will practice recognizing and writing numbers 11–20. They will also relate these numbers to addition expressions and equations. No expressions or equations are used in this section.
Represent quantities up to 20 with a written number.
Section Narrative
In this short section, students count groups of up to 20 images arranged in lines, arrays, circles, and on 10-frames.
Images arranged in a circle can be more challenging to count, motivating a greater need to keep track of what has been counted. Students use their understanding that teen numbers are composed of 10 ones and some more ones to help them count and keep track of groups of up to 20 images. They then write numbers to represent such quantities.
Throughout this section, students should have continued access to the reference sheet that shows numbers 11–20 with dots in 10-frames.