The first unit revisits and extends addition and subtraction within 20, helping to ensure that second graders operate with understanding and fact fluency from the start of the school year.

Units 2, 3, 5, and parts of Unit 7, are devoted to place value and multi-digit addition and subtraction. During these units, students learn to count by fives, tens, and multiples of hundreds, tens and ones; read, write, and compare numbers to 1,000; and develop fluency with addition and subtraction to 100 as they solve and pose a wide variety of word problems. Later in the year, the children use concrete models and sketches, as well as strategies based on place value, properties of operations, and the relationship between addition and subtraction, to add and subtract to 1,000.

Unit 6 revolves around geometry, building foundations for understanding area, volume, congruence, similarity, and symmetry as students investigate, describe, build, draw, combine, decompose, and analyze two- and three-dimensional shapes.

Unit 4, and the first part of Unit 7, focus on linear measurement, as students construct their own rulers; estimate and measure in inches, feet, yards, centimeters, and meters; and solve problems that involve adding, subtracting, and comparing lengths.

Unit 8 revisits linear measurement in the context of science and engineering as students make and test cardboard ramps of different kinds to investigate some of the factors that cause marbles to roll farther and faster. In the process, they generate data by measuring marble roll distances multiple times, pool their data, and enter it on line plots to better see, understand, and analyze how manipulating the different variables affects the outcomes.