CKMath Unit 5: Adding Within 100
Focus:
In this unit, students add within 100, using place value and properties of operations in their reasoning. Students begin by adding a two-digit number with another two-digit number or with a one-digit number where it is not necessary to compose a new ten. Then, they observe cases in which adding some ones together require composing a new ten. Two broad methods for finding sums are explored: adding on by place (adding on tens, then ones), and adding units by place (combining tens with tens and ones with ones). To make sense of methods for adding (especially as it relates to composing a ten when adding ones and ones), students work with a variety of representations—connecting cubes in towers of 10 and singles, base-ten drawings, expressions, and equations. They also use different representations to share their thinking with others. Expressions and equations are presented horizontally here to encourage students to make sense of the numbers and ways of adding rather than apply an algorithm. Eventually, they write equations to represent their thinking. Students are not expected to write or use equations in any specific way. Even in activities that focus on interpreting and writing equations, students have continued access to drawings and other tools for sense making.
Number of Lessons: 13 and 1 optional
Instruction Time:
Approximately 60 minutes
(Please note that each lesson is designed for one instructional block, and may be divided into shorter or longer segments based on teacher pacing and student needs.)
Additional Search Terms:
place value • properties of operations • associative properties • commutative properties
