Estimation
"We always need more people who can think," were the closing words of an article I just read by
Robert J. Doman Jr. Who can argue with that?!? Estimation in math does just that, helps people think. When you estimate you go beyond rote memorization, you are not just applying a meaningless formula. What you are doing is asking, "what is the value of these symbols," and, "does this make sense?" It helps you to understand the concept and it's applicable meaning.
Two other benefits of estimation, Dorman points out, are visualization and conceptualization.
When a student is completing a math problem often it is helpful for them to visualize or conceptualize it in some sort of real-world situation, forming a mental picture. Associating meaning to math is very helpful to children, particularly in the primary grades. For example, if I ask a 2th grader what 5-7=? I may be met with a blank stare. If I phrase the question as a familiar situation,"If you are at the toy store with your mom and you see a toy that costs $7.00, but you only have $5.00 with you, how much do you owe your mom when you get home?" The child will quickly respond, "Oh, that's simple, I had to borrow $2.00 from her," they understand better when it is a situation that they can relate to, one that they can envision.Teaching Estimation
Estimation by rounding
When a student is asked to estimate in a simple computation problem, often what the question is asking them to do its round. Rounding is also a handy skill when checking over problems. If a student ends up with 97 when subtracting 406 from 603 he or she can quickly assume that is not a reasonable answer. This quick check prompts them to take a closer look, noticing that they simply forgot to bring complete the last step and place a one in the hundreds place.
Estimating Length or Distance
Now, here's a concept best taught hands-on. Get out the rulers & meter sticks! Comparisons of things of different lengths, which is larger or smaller, taller or shorter will give them a real-world idea of what these measurements actually mean.
Maps are another helpful tool when teaching distance estimation. Plotting multiple points on a map and asking a question such as, "The Jones family is planning a trip. They have a budget of $290 to spend on gas for their vehicle that gets approximately 30 per gallon. If the price of gas is $2.89 per gallon which destinations on their wish list are options for their trip? (Don't forget, they have to get back home!)"
Estimating Numerical Value
What is 76? Well, it's more than 50, which would be half way between 0 and 100, that's a good start. Conceptualizing where a number lies in relation to other numbers. This concept is helpful in teaching anything from beginning addition to decimals and fractions!
Useful Links in Estimation:
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| http://www.math.com/ |
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| http://nacd.org/newsletter/0309_estimation.php |
Some estimation and rounding online practice can be found at:
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| http://www.aaamath.com/est.htm |
Visit:
http://www.transum.org/ For a list of Maths lesson starter activities and interactive exercises for students on the topic of Estimating. Free for students and teachers!
And, finally, the most useful article I found:
Developing Estimation Skills in the Primary Grades
Fantastic teaching strategies and activities!
