Decimals—Adding and Subtracting

Do you find that your middle school students still become confused with decimals? Not unusual! The resources here offer support in explaining the concepts underpinning addition and subtraction of decimals, in particular, place value. They also include demonstrations of addition and subtraction and opportunities for practice. The goal for students, as stated in NCTM’s Focal Points, is to develop fluency with computing, solving problems, and making reasonable estimates. I hope these resources will visually and interactively engage your students, helping them toward that goal. 

If you have found other digital resources that have helped your own teaching of this topic, please take a moment to share with your colleagues. Just leave a comment below! 

Builder Ted
This interactive game deals with place value in decimals, necessary to understanding addition and subtraction. In the game scenario, students help Builder Ted by placing numbered bricks on a ladder in numerical order. At the first level of difficulty, all numbers are positive, but the two higher levels include negative numbers as well. If a number is placed incorrectly, all the bricks immediately fall and the player begins again.  

Place Value
The user can type in any number, such as 3601.076, or let the computer choose a number. As the student passes the mouse over each digit in the number, its place value is shown. Also, how to say the number is given, plus a short exercise asking the student to identify the digit in, say, the thousandth position.

Fractions, Decimals, and Percentages
Especially appropriate for tutoring or even review, the site introduces decimals (reading, writing, and comparing) and then offers examples and practice in operating with decimals.

Base Block Decimals
With this virtual manipulative, students can explore the meaning of place value and grouping as they add and subtract decimals. The base blocks can represent negative as well as positive numbers with one to four decimal places. Students exchange and group the blocks as needed to solve the problems created by either the student or the computer. All material is available in Spanish and French as well as English, including instructions for using the manipulative, information about bases and place value, and suggested questions for classroom use.

Decimals
This site offers bare-bones explanations of decimal topics and interactive practice. In the long list of topics are adding and subtracting decimals as well as adding and subtracting money. The computer sets the problem and gives immediate feedback to the student’s response. The bottom of each lesson page contains timed exercises.


We Want Your Feedback
We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org. Post updated 11/29/2011.

Those Dicey Decimals!

Understanding decimals is a “must” and practice with them a basic necessity. The first two resources here feature games that encourage practice at varying levels of mastery. The third site offers a visual, interactive experience in comparing decimal values, while the last site provides short, self-contained lessons and practice on individual topics.

MathFROG
MathFROG stands for Math Fun, Resources, and Online Games. These lessons combine online mathematics games with paper-and-pencil follow-up exercises. Among the lessons listed for grade 6 are Decimal Mania, Decimultiplication, Place Value! and Ordering Decimals.

The Math Files Game Show
Students practice decimal skills as they play these games: Saloon Snap (matching fractions with decimals and percents), Builder Ted (ordering numbers), and Rounding Off (to significant figures or decimal places). Three levels of difficulty allow students to increase the challenge

Comparing and Ordering Decimals
In this interactive investigation, students use grids to model decimal numbers and compare them graphically. They then compare the numbers on a number line. The visual experience aids in making real sense of decimals. This is a subscription site; however, a free month of viewing is available.

Decimals
This site has basic explanatory lessons and interactive practice dealing with decimals. Topics include naming decimals; adding, subtracting, multiplying, and dividing decimals; rounding decimals; place value of decimals; comparing decimals; finding percents; equivalent fractions and decimals; and much more!

We Want Your Feedback
We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org. Post updated 4/14/2012.