Principles and Standards for School Mathematics
Number and Operations Standard
Compute fluently and make reasonable estimates
Expectations (6 - 8)
select appropriate methods and tools for computing with fractions and decimals from among mental computation, estimation, calculators or computers, and paper and pencil, depending on the situation, and apply the selected methods;
Use mathematical models to represent and understand quantitative relationships
Expectations (9 - 12)
use symbolic expressions, including iterative and recursive forms, to represent relationships arising from various contexts;