Big Ideas: Decimal place value is an extension of whole number place value. The decimal point indicates part of a whole. Decimals are a simpler way of writing fractions. Each place value is ten times greater than the one to the right. Adding decimals is the same as adding whole numbers. This lesson builds on the students' understanding of whole number addition and relates it to addition of decimals. In this lesson, students will use a variety of strategies to add decimals and whole numbers. Strategies may include, but are not limited to: number line diagrams, base ten models, decimal grids, and the standard algorithm. Students should be able to model their thinking in multiple ways. When adding decimals it is important for students to realize that the same rules apply to that of adding whole numbers. Vocabulary: add, addend, sum, estimate, partial sums Special Materials: Base Ten Blocks White Boards and Dry Erase Markers (optional) Decimal Grids Open number-lines