To: Teacher2Teacher Public Discussion
Subject: Re: estimation strategies
Dear Julian, I am glad you are working with your son, and commend you for your use of our site to find out more about teaching mathematics. As for your comments about front end estimation, I would respectfully disagree with you. Rounding is not the only way to determine estimates. In real life people estimate in a variety of ways, and the accuracy needed is determined by the reason for the estimate in the first place. It is important that children learn that they must consider the context in which they are working plays a part in the strategies they choose to solve a problem. Front end estimation can be considered a precursor to rounding, since it uses the leading digits, and doesn't involve any changing of amounts. The numerals are right there to be seen and used. It is a great way to introduce estimation, and as students become more proficient with using just the leading digits, the skill of making adjustments should be introduced. It is just another way to find a reasonable answer. And, having said that, I would also like to remind you that there is not really any such thing as a "wrong" estimate... some estimates are less useful than others... but any estimate made using the original problem is a valid estimate. And when we are talking about teaching students to estimate, the goal is not to find the one correct "estimate" (and prove you can regurgitate the teacher's exact method), but to have the skill to reason about the numbers being used, and to be able to come up with a range that is suitable for using to predict the answer, to have a quick and easy-to-do method for checking to see what a reasonable answer would be. It is more useful to me, as a teacher, to see how my students are thinking about the problems they are trying to solve. And it is more useful to them to have a variety of strategies to use, and to know they have the power to solve whatever is put in front of them. The other day one of my fifth grade students commented to me as she viewed a problem involving area and perimeter, "There must be a way to figure this out." In September, this same student wouldn't even attempt a problem unless she knew "the 'right' way to solve it". You are not the only parent frustrated by helping a child with estimation. Many adults were taught that there are always (and only)exact answers to math questions. This can make it difficult to work with an unfamiliar curriculum where more is valued than just the correct answer, where sometimes the answers are numerous, and where the strategies for solving the problem vary with the ability of the solver. On top of that, you are, unfortunately, right that not all teachers are able to explain the concept well. I would urge you to talk with your son's teacher, to try to gain some insight into what is being done in the classroom. Again, I thank you for your interest in what your son is learning. I wish all my students had parents who wanted to be an active part of their child's education.
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