In this section, students count and compare collections of up to 20 objects. The focus is on the count sequence up to 20 and using it to determine 1 more or 1 less than a given quantity or number, both with and without a context.

Compare the groups of objects. 
Explain how you know which group has more objects.

There are 10 people on the bus. Then 1 person gets off the bus.
How many people are on the bus now?

1, 2, 3, 4, 5, 6, 7, 8, 9, 10

Many of the activities in this section are optional because the standards do not expect students to compare quantities or numbers greater than 10. This work prepares students to relate counting to addition and subtraction in grade 1.

In this section, students develop fluency with adding and subtracting within 5. Repeated practice with different compositions of numbers to 5 prepares students to fluently find the values of addition and subtraction expressions.

In the final lesson, students apply what they learned, using objects and equations to find the unknown part of an equation with a total of up to 5.

In this section, students explore and describe the math around them. They participate in activities that allow them to notice, record, ask questions, and tell stories about math in their community.

First, students record quantities that they see in their school as they make their own number book. Next, they ask and answer their own mathematical questions, such as: “How many tiles are there from the office to the cafeteria?” or “Are there more doors or more windows in the library?"
 

Finally, students create, share, and solve story problems about their environment and community. While the school building is used as a context, the activities in this section can be adapted for students to do in their home community.

In this section, students work with 10 as a benchmark when working with numbers within 20. This work prepares them to add within 20 in grade 1, where students will be encouraged to make a ten.

The section begins with students composing and decomposing 10 in different ways and representing these compositions and decompositions with equations. Students then find the number that makes 10 when added to any given number. They also use their understanding of the magnitude of 10 to estimate if groups have more than or less than 10 items.

Throughout the section, students use fingers, objects, drawings, 10-frames, and equations to represent their thinking. They also create a tool with 5 of each color bead to show different compositions of 10.

Finally, students compose and decompose teen numbers 11–19, always working with a group of 10 ones and some more ones.

“How many students will sit at the table? How many will sit on the rug?
How many students are there altogether?”