Third grade is a bridge year. Children develop mastery in their work with whole number addition and subtraction and begin multiplication, division and fractions. Addition and subtraction work focuses on multi-digit computation strategies using multiples of ten and combinations that add to 100. By the end of third grade, children should have mastered addition and subtraction fact combinations to 20.

Third graders investigate the properties of multiplication and division and develop strategies to solve problems. Work focuses on computation using equal size groups and an introduction to rectangular arrays. Conceptual work with fractions also begins in third grade.

Third grade children collect, represent, describe and interpret data. They learn to represent data with line plots and bar graphs. Children learn to measure perimeter and area of shapes. They work with standard and metric systems.

Changes for the 2009-2010 School Year
Some of the units listed below are supplemented with materials from the National Council of Teachers of Mathematics (NCTM) and Bridges in Mathematics to meet curricular gaps caused by changes in the State of Washington math standards. New curricula that strongly match the new standards are being piloted this year and are expected to be adopted and implemented in the fall of 2010.

Computational fluency in third grade
The computing skills that third graders will learn and be able to do easily by the end of the year: Third Grade Computation Strategies