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Thursday, April 26, 2012

Estimating With Decimals - Interactive Math Lesson

Lesson: Estimating With Decimals
Objective: Estimate sums of decimals
Grade: 5-6
File: Interactive Powerpoint Presentation and pdf

Contents Summary:

Review on Rounding decimal numbers:
-Identify the place you are rounding to, and place a circle around it.
-Check the digit to the right.  If it is more than or equal to 5, then the number in the circle increases by one.  If it is less than 5, then the number in the circle stays the same.
-Keep everything before the circle.  Everything after the circle becomes zero.  If the zeroes come at the end of a decimal, they can be dropped.

Different strategies in estimating decimals:
1. Estimating to the nearest whole number - Round to the ones place, and drop the decimal part of your number.
2. Front end Estimation - a. Add the “front-end” digits, ignoring the decimals. b. Estimate the decimals. c. Add the decimal estimate to the front-end sum.
3. Estimating Using Rounding - Round each decimal to a designated place value, then add to estimate the sum.

More examples are in the presentation.

Estimating With Decimals - Interactive Powerpoint Presentation

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