For many second graders, the beginning of the year is a time for revisiting knowledge and skills learned in first grade.  The summer months away from mathematics instruction along with little opportunity for practice and guidance sometimes means a loss of strong understanding of concepts.  Addition and subtraction of numbers to 100 is a Common Core Standard for first-grade students, although many struggle with this fundamental concept even throughout second grade.  This curriculum unit is designed to increase students' understanding of the number line as a tool to help them master two-digit addition and subtraction, improve their base-ten number sense and increase their fluency in mathematical operations.

(Developed for Mathematics, grade 2; recommended for Mathematics, grade 3)