Objective: Estimate sums and differences using benchmark numbers.
Lesson 29 focuses on the process of using benchmark numbers to estimate sums and differences of mixed numbers. Students once again call on their understanding of benchmark fractions as they determine, prior to performing the actual operation, what a reasonable outcome will be. One student might use benchmark whole numbers and reason, for example, that the difference between 4 1/5 and 1 3/4 is close to 2 because 4 1/5 is closer to 4 than 5, 1 3/4 is closer to 2 than 1, and the difference between 4 and 2 is 2. Another student might use familiar benchmark fractions and reason that the answer will be closer to 2 1/2 since 4 1/5 is about 1/4 more than 4 and 1 3/4 is about 1/4 less than 2, making the difference about a half more than 2, or 2 1/2 .
There may be cases when our downloadable resources contain hyperlinks to other websites. These hyperlinks lead to websites published or operated by third parties. UnboundEd and EngageNY are not responsible for the content, availability, or privacy policies of these websites.