Throughout our curriculum there are activities that utilize rounding and estimation to help show that the answer is reasonable. This seems to be the scaffolding for that infamous last question on every the unit test: The Extended Response.
Examples from 5th grade: -Explain how you know your answer is reasonable (Unit 1) -Explain how you found your answers (Unit 2) -Explain how you know (Unit 3) -Explain (Unit 4) -What do you do with the remainder (Unit 5...I like this one!) I'm guessing that 5th grade assessments are not the only ones that include these questions. The problem with this structure is that the estimation is still disconnected from the real world. At Graham Fletcher's NCTM session in Chicago he demonstrated that a room full of math teachers were not very good at estimating. With a number line from 0 to 1 trillion and a dot on the far right, he asked all in the room to stand up. He shared that the dot was going to move backwards down the number line and we should sit down when the dot reaches 1 billion. Most in the room sat down at the halfway mark and the rest sat down long before the correct spot. *Take a moment to draw that number line and mark where 1 billion is. His message was that we need to be doing number sense and estimation activities daily. Ones that connect to the real world and beyond that final question on the unit test. The best resource for estimation is from Andrew Stadel. His site is called Estimation 180 and is a collection of pictures and videos that students can relate to (bacon, halloween candy!) The activities build upon one another, day after day, so that students use previous reference points to guide their estimations. Once they are using benchmarks, they are no longer guessing. A strategy to use while facilitating is to ask students for their range, including a "too low" and a "too high." Ask them to use benchmarks from previous activities or real world experiences to explain their claims. One note from Graham is to not accept unreasonable answers like 0 or "a million." Guide students to stake a claim based on evidence so that their estimations have value. The day after returning from NCTM, I was waiting at the Harding's deli and the women next to me was eyeing the parmesan chicken. She was asking the weight of one chicken piece. She was worried that one piece would be 1 pound and cost close to $8. I could not have made up her quote, "I'm just not that good at estimating." So I pulled out my phone and asked her if I could take a couple pictures, because I had just noticed an estimation activity! Comments are closed.
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Matt HawkinsGull Lake Middle School Archives
March 2018
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