Determining the Reasonableness of Sums and Differences Using Benchmark Fractions

This lesson teaches how to determine the reasonableness of sums and differences using benchmark fractions. It covers the concepts of numerators and denominators, introduces benchmark fractions, and explains how to use them for estimation. The lesson uses real-world examples, such as money and word problems, to illustrate how to round fractions to the nearest half and apply estimation in practical scenarios. Students learn to check the reasonableness of calculations by rounding fractions and using benchmark numbers.

What does the numerator in a fraction represent?

• The total number of parts in the whole

• The value of the fraction

• The position of the fraction on a number line

• The number of parts being considered

Which of the following is a benchmark fraction?

• 1/3

• 2/3

• 1/5

• 1/2

How many decorations did the students in the craft club make?

• 48

• 54

• 102

• 1000

What is the purpose of rounding fractions to the nearest half?

• To simplify fractions

• To convert fractions to decimals

• To find exact answers

• To estimate sums and differences

If 1/6 is rounded to the nearest half, what is the result?

• 1/2

• 1/4

• 1

• 0

Sophia's hermit crab eats 1/9 of a cup of rice and 6/10 of a cup of fruit. What is the estimated total amount of food it eats per week?

• 1/4 cup

• 1/2 cup

• 3/4 cup

• 1 cup

In the example of Tyler mowing the lawn, why is his father's claim of 3/7 unreasonable?

• Because 2/5 and 1/2 add up to more than 3/7

• Because 3/7 is less than 1/2

• Because 3/7 is more than 1

• Because 2/5 and 1/2 are not benchmark fractions