# Fractions: Multiplying and Dividing

Is there anything more difficult to explain at 5th and 6th grade level than the rules for multiplying and dividing fractions? These resources offer support in explaining the concepts that underlie the rules. Visual, interactive models are provided where possible. You will also find opportunities for your students to practice their skills in this area of arithmetic. If you have other approaches to teaching this topic, please share! Just use the comment box below!

Multiplication of Fractions
Visualize and practice multiplying fractions using an area representation. With the “Show Me” option selected, the virtual manipulative is used to graphically demonstrate, explore, and practice multiplying fractions. A rectangular grid, representing a whole, shows the areas of two fractions to be multiplied, one fraction in red on the left and another in blue at the bottom. The area of the overlapping region, shown in purple, represents the product of their multiplication. The “Test Me” option provides problems to be solved using the same graphical representation.

Multiplying Fractions
This tutorial site offers instruction as well as practice in multiplication of fractions. The fractions are modeled with either circles or lines (rectangular areas). The visual display matched with the numerical makes an effective demonstration.

Divide and Conquer
This lesson is based on the idea that middle school students can better understand the procedure for dividing fractions if they analyze division through a sequence of problems. Students start with division of whole numbers, followed by division of a whole number by a unit fraction, division of a whole number by a non-unit fraction, and finally division of a fraction by a fraction. Activity sheets and guiding questions are included.

Dividing Fractions
In this activity, students divide fractions using area models. They can adjust the numerators and denominators of the divisor and dividend and see how the area model and calculation change. Full access to ExploreLearning is available through an annual subscription, but you can apply for a month’s free access in order to test out the applets.

Fraction Bars
This applet offers a classroom-adaptable idea of how to explain division of fractions. Adjustable colored bars are used to illustrate arithmetic operations with fractions on the number line. The initial seeding shows a division problem, dividing 7/5 by ½.

As teachers, we all want our students to understand those concepts underpinning addition and subtraction of fractions— the concept of equivalent fractions, in particular. These resources offer teaching ideas on both the concepts and the skills, including demonstrations of addition and subtraction as well as problems for practice. I looked hard for material that would visually or interactively engage middle school students. If you have ideas to share on how you teach these operations, please use the comments area to put them online.

Visual Fractions
An exceptional tutorial on fractions, including step-by-step, illustrated explanations of addition and subtraction. Both circle and line models help students visualize the operations with like and unlike denominators. Interactive problems allow students to use these visual models as they figure the numerical answers.

Students must do the usual exercise of finding equivalent fractions with common denominators, but here the fractions are represented visually as portions of a square. Once the computer checks that the fractions are correct, students can drag the representations into a third box and enter the sum of the fractions. This is a real learning experience!

The Fractionator
Created by math teacher Jeff LeMieux, the site offers online and offline tools to help students understand fractions. The online tools use unit squares to model two fractions to be added (or subtracted) and then create equivalent fraction models; with this visual aid, students complete the operation. They can request a new problem for each exercise or enter the two new fractions themselves. Also provided are links to printable materials.

Soccer Shootout
Practice time! Students can practice the addition and subtraction of fractions at levels of difficulty ranging from Easy to Super Brain. Students play against the computer and are provided with a full solution when a wrong answer is entered.

Classic Middle-Grades Problems for the Classroom
The king finds a bowl of mangoes and eats 1/6 of them; the queen eats 1/5 of the remaining mangoes; the prince eats 1/4, etc., until only 3 are left. How many were in the bowl to begin with? A complete lesson plan is given, including activity sheets. A thought-provoking problem to cap this work on fractions!

# Close Encounters with Ratios

Understanding ratio and proportion, one of NCTM’s Focal Points for grade 7, presents a real challenge for all levels of middle school. Here are classroom-friendly ways to explore the topic from several angles. Each involves visuals or hands-on activities that bring students into close contact with the abstract concept of ratio. Let other teachers hear your ideas on teaching this topic! Post a comment below.

Constant Dimensions
In this carefully developed lesson, students measure the length and width of a rectangle using standard units of measure as well as nonstandard units such as pennies, beads, and paper clips. When students mark their results on a length-versus-width graph, they find that the ratio of length to width of a rectangle is constant, in spite of the units. For many middle school students, not only is the discovery surprising but also opens up the whole meaning of ratio.

Discovering the Value of Pi
Students measure the diameter and circumference of several circles, using a handy applet, record their data, and reach conclusions about the ratio of circumference to diameter. A genuine guided exploration!

Math-Kitecture
Math-Kitecture is about using architecture to do math (and vice versa). Activities engage students in doing real-life architecture while learning estimation, measuring skills, proportion, and ratios. In Floor Plan Your Classroom, for example, exact directions are set out and illustrated on how to make a copy to scale of your classroom.

What’s My Ratio?
What would happen to a picture in the pocket of someone who is shrunk or enlarged? This question hooks students into a study of similar figures. As they compare the measurements of corresponding parts of pictures that have been either decreased or increased in size, they can investigate concepts of similarity, constant ratio, and proportionality.

Figure and Ratio of Area
A page shows two side-by-side grids, each with a blue rectangle inside. Students can change the height and width of these blue rectangles and then see how their ratios compare — not only of height and width but also, most importantly, of area. The exercise becomes most impressive visually when a tulip is placed inside the rectangles. As the rectangles’ dimensions are changed, the tulips grow tall and widen or shrink and flatten. An excellent visual experience!

Capture-Recapture: How Many Fish in the Pond?
To estimate the number of fish in a pond, scientists tag a number of them and return them to the pond. The next day, they catch fish from the pond and count the number of tagged fish recaptured. From this, they can set up a proportion to make their estimation. Hints on getting started are given, if needed, and the solution explains the setup of the proportion.

Size and Scale
This is a challenging and thorough activity on the physics of size and scale. The final product is a scale model of the Earth-moon system, but the main objective is understanding the relative sizes of bodies in our solar system and the problem of making a scale model of the entire solar system. The site contains a complete lesson plan, including motivating questions for discussion and extension problems.

Scaling Away
For this one-period lesson, students bring to class either a cylinder or a rectangular prism, and their knowledge of how to find surface area and volume. They apply a scale factor to these dimensions and investigate how the scaled-up model has changed from the original. Activity sheets and overheads are included, as well as a complete step-by-step procedure and questions for class discussion.

# Factors

Factors and their multiples are so important to students’ work with fractions and number theory. These concepts come under the National Council of Teachers of Mathematics (NCTM) Number and Operations Standard for the middle grades. The resources here are all hands-on, if only virtually. Important to their success is the classroom talk that the resources generate.

The Factor Game
This is more than a game; it is a full lesson plan, complete with handouts, including the game board, and questions for discussion. Students practice finding factors and then analyze the winning strategies. It’s this analysis that leads them to talk about prime, composite, abundant, deficient, and perfect numbers. The plan is downloadable and printable. (See the online version below.)

The Factor Game (i-Math Investigations)
This is the same game but online and interactive. One advantage here is that a single student can play against the computer. What is missing, however, is the winning strategy analysis, so rich in discussion. If you decide to use this version, you can simply borrow the discussion questions from the pdf version above.

Coloring Multiples in Pascal’s Triangle
Good practice in finding multiples of small factors! Students roll a number cube, then color in the multiples of that number in Pascal’s triangle. As they click on all the multiples of the number rolled, they also practice multiplication and observe the surprising patterns that form in the triangle.

The activity starts with building a factor tree, but then moves to finding common factors and reviewing those old friends: GCF (greatest common factor) and LCM (least common multiple). The student must first find the prime factors for a pair of numbers. After two factor trees are built, the student drags the prime factors from each tree to a Venn diagram, showing the common factors of the two numbers in an overlapping area. Finally, the student enters the greatest common factor and the least common multiple, which can be checked immediately. This activity is interactive, visual, and good review!

# Action with Fractions!

Really understanding what fractions are, how they fit on the number line, and how to operate with them – add, subtract, multiply, divide – is central to learning decimals and percentages. According to the NCTM Principles and Standards, students in the middle grades should be expected to acquire a deeper understanding of fractions, decimals, and percents and an increased flexibility in using them to solve problems. Yet students may reach even the higher grades of middle school without a firm grasp of fractions. Perhaps a change in strategy could help? Let’s offer compelling visuals and hands-on manipulation of those fractured numbers!

COUNTDOWN: Number and Operations – Fractions
COUNTDOWN is an interactive television math program broadcast on cable television in Chicago. This web site contains the archives of those broadcasts. The 4-7 minute math movies consist of direct instruction and are reinforced with literature, manipulatives, activities and related computer instruction. Topics include logic, perimeter, area, probability, graphing, congruence, integers and much more. Movies are organized according to content standards established by the National Council of Teachers of Mathematics. Many of the movies have associated worksheets that can be printed.

Visual Fractions
A thorough tutorial on the topic—from identifying and comparing fractions to operations with them! Students work through interactive exercises and games. A complete step-by-step, illustrated explanation of each subtopic is included. Don’t miss the game of Finding Grampy, where students practice finding a mixed number in lowest terms as they look for Grampy on the number line.

Fraction Sorter
Using this online manipulative, students represent two to four fractions—such as 7/13, 2/7, 8/9, and 2/3—by dividing and shading areas of squares or circles. They then order the fractions from smallest to largest on a number line. The visual representation here is powerful.

National Library of Virtual Manipulatives
Under the middle school offerings, you will find the activity Adding Fractions. Students must do the usual exercise of finding equivalent fractions with common denominators, but here the fractions are represented visually as portions of a square. Once the computer checks that the fractions are correct, the students can drag the representations into a third box and enter the sum of the fractions. This is a learning experience! There are other activities on fractions as well, all worth checking out.

The Maths File Game Show
This BBC site offers a game that requires players to match fractions with equivalent decimals or percentages, Go to Saloon Snap. When a question is answered correctly, the player can move his or her piece across the board. The goal is to be the first to create a path across a 10-by-10 grid. It’s a real math exercise and it’s motivating!