Investigate Fractions Tasks
There’s something weird about fractions. If the numerator, which is the top, is the same, the bigger the denominator the smaller the fraction.
 Jordan, grade 5
Like Jordan, many students feel that “there’s something weird about fractions.” This section explores students’ challenges with fractions, by examining three tasks and related student responses. Two of these tasks come from the National Assessment of Educational Progress (NAEP).
 If working with a team, we recommend that team members individually solve each of the three tasks shown below, before sharing and discussing your solutions and your ideas about how students might approach each problem. Each task is downloadable.
Problem 1: Estimate the answer to . You will not have time to solve the problem using paper and pencil. (Take some notes on your solution method.)
Use the buttons below to view and hide solutions to Problem 1  
Discussion Questions:
 How did you solve the problem and how might students solve the problem?
 What insights into fractions make quick work of solving this problem?
 Discuss why students chose each of the responses shown above.
 Why do so many students find this problem difficult?
Problem 2: Find two fractions between and 1.
Use the buttons below to view and hide solutions to Problem 2  
Discussion Questions:
 How did you solve the problem and how might students solve the problem?
 What understandings and misunderstandings about fractions might this problem reveal?
 What do the student responses (above) suggest that each student understands and does not understand about fractions?
 Do you notice any differences in the responses of students who used the basal textbook and the students who participated in the “Measure Up” curriculum?
Problem 3: Jim has of a yard of string which he wishes to divide into pieces, each of a yard long. How many pieces will he have?
Now that you have solved three different fraction tasks and considered student solutions, we suggest that you:
 Briefly summarize your insights into the question “What is difficult for students about fractions?”
Table 1 lists six different aspects of fraction number sense, with examples of student understanding of each.
 Read through Table 1 individually and focus on the connection between the two columns (the type of knowledge and the examples of student difficulty or understanding). Identify any that:
 Are puzzling or particularly interesting to you.
 Help you think about any of the student solutions to problems 1 – 3 that you examined.
 Discuss or make notes on these.
Table 1: What’s Hard About Fraction Number Sense?
Type of Understanding or Knowledge  Example of Student Difficulty or Understanding 
A Fraction is a Number A Fraction represents an amount, not just pieces (such as 2 of 3 pieces of pizza) or a situation (such as 2 of 3 shirts are red).  When asked to put the fraction on a number line, a student said, “you can’t put it on the number line because it’s two pieces out of three pieces, it’s not a number.” [Or “ is not a number, it’s two numbers.” 
Partitioning Fractions


The Meaning of the Denominator
The Meaning of the Denominator (cont.)


Knowing What is the Whole




Fractions Can Represent Quantities Greater Than One May be difficult for students who have a strong image of a fraction as a piece of something. 

Kerslake, D. (1986). Fractions: Children’s strategies and errors. A report of the strategies and errors in Concepts in Secondary Mathematics and Science Project. Windsor, England: NFERNelson. Behr, M.J. & Post, T.R. (1992). Teaching rational numbers and decimal concepts. In T.R. Post (Ed.), Teaching mathematics in grades K8, researchbased methods (pp. 201248). Boston: Allyn and Bacon.
Student work from Work Session presented by Barbara Dougherty and Barbara Fillingim, NCTM Annual Meeting Research Presession, April 21, 2009, Washington D.C., reproduced by permission of first author. Footnote (3) provides more information on the “Measure Up” curriculum.
The “Measure Up” curriculum emphasizes use of units of length, area, and volume to explore basic mathematical ideas such as equivalence. For example, students might compare two lengths by using a third length. Students using this curriculum become very attuned to asking, “What is the unit?” since different units (such as a hexagon and six triangles) might be used to create equivalence.