CMP3 Goals for Let's Be Rational, Problem 2.2
Understand that estimation is a tool used in a variety of situations including checking answers and making decisions, and develop strategies for estimating results of arithmetic operations. Use benchmarks and other strategies to estimate results of operations with fractions. Use estimates to check the reasonableness of exact computations Give various reasons to estimate and identify when a situation calls for an overestimate or an underestimate. Use estimates and exact solutions to make decisions.
Revisit and continue to develop meanings for the four arithmetic operations and skill at using algorithms for each. Determine when addition, subtraction, multiplication, or division is the appropriate operation to solve a problem. Develop ways to model sums, differences, products, and quotients with areas, fraction strips, and number lines. Use knowledge of fractions and equivalence of fractions to develop algorithms for adding, subtracting, multiplying, and dividing fractions. Write fact families with fractions to show the inverse relationship between addition and subtraction, and between multiplication and division Compare and contrast dividing a whole number by a fraction to dividing a fraction by a whole number. Recognize that when you multiply or divide a fraction, your answer might be less than or more than the numbers you started with. Solve real-world problems using arithmetic operations on fractions.