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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)
- Jahiderles Yudith Ching Castillo (Burleson Elementary, Dallas , Te)
Subject taught: Math, Grade: 2
Excellent progression from concrete to pictorial.
I will embed the sentence strips and base ten blocks to explain another way to add coins. I explained this week to my colleagues that the number line can even be used as a visual representation to add coins. We agreed that as long as we clarify to the students what units are involved (cents), this will not confuse students when they get to higher grade levels and have to work with decimals. Meaning, the 1 will represent a dollar and the intervals will be 1/10 of a dollar.
This article also gave me the idea of using the Cousinaire rods to introduce the term multiples.
The collaborative work that can be done among students exploring Cousinaire rods is extraordinary in the sense of developing conceptual understanding of units of measurement, relationships, and patterns.