Focus:
In this unit, students are introduced to the number line, an essential representation that will be used throughout students’ K–12 mathematical experience. They learn to use the number line to represent whole numbers, sums, and differences. They see that the tick marks and numbers on the number line are like those on a ruler: both show equally spaced numbers that represent lengths from 0. Students use this understanding of structure to locate and compare numbers on the number line, as well as to estimate numbers represented by points on the number line. Students then learn conventions for representing addition and subtraction on the number line: using arrows pointing to the right for adding and arrows pointing to the left for subtracting. Students also use the number line to represent addition and subtraction methods discussed in Number Talks, such as counting on, counting back by place, and decomposing a number to get to a ten. The reasoning here deepens students’ understanding of the relationship between addition and subtraction.
Number of Lessons: 12 and 3 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:
number line • directional arrows • place value • properties of operation
