Four of eight units are devoted to addition and subtraction within 20. They help students gain fluency with facts to 10 and develop increasingly sophisticated strategies for solving addition and subtraction combinations to 20. During these units, students model, solve, and pose a wide variety of word problems to construct meaning for the operations of addition and subtraction, as well as an understanding of how the two are connected.

Two of the eight units focus on place value, extending the counting sequence to 120 as students learn to think of whole numbers between 10 and 100 in terms of tens and ones. Much of the work in these units engages first graders in developing, discussing, and using efficient, accurate, and generalizable methods to add within 100 and subtract multiples of 10.

The remaining two units revolve around geometry and measurement. The geometry unit challenges children to identify, describe, construct, draw, compare, compose, and sort shapes. Students also learn about fractions in the context of two-dimensional shapes. The measurement unit provides ample opportunity for students to develop an understanding of the meaning and processes of measuring time and length as they conduct duration experiments; construct, fly, and measure the flight distances of paper gliders; and investigate some of the many ways in which they have grown and changed since they were born.