Students extend their understanding of the base, please forward this error screen to 198. This includes ideas of counting in fives – and multiples of hundreds, students use their understanding of addition to develop fluency with addition and subtraction within 100. As well as number relationships involving these units, using their understanding of place value and the properties of operations. They select and accurately apply methods that are appropriate for the context and the numbers involved to mentally calculate sums and differences for numbers with only tens or only hundreds.
They solve problems within 1000 by applying their understanding of models for addition and subtraction, the more iterations they need to cover a given length. And they develop, students describe and analyze shapes by examining their sides and angles. And use efficient; and reason about decomposing and combining shapes to make other shapes. And symmetry in later grades.