fraction model.
c. “Express whole numbers as fractions, and recognize fractions that are equivalent to whole numbers.
d. “Compare two fractions with the same numerator or the same denominator by reasoning about their size. Recognize that comparisons are valid only when the two fractions refer to the same whole. Record the results of comparisons with the symbols or and justify the conclusions, e.g., by using a visual fraction model.”
Background
Fractions may be expressed in many forms. Two common forms are equivalent fractions (fractions that have the same value) and whole numbers (which can be written as a fraction with 1 as the denominator).
If two fractions have the same numerator, the fraction that has the larger denominator has the smaller value. For example, is less than Given two pies of equal size, cut one into thirds and the other into halves. It is clear that a piece that is of the original pie is smaller than a piece that is of the original pie.
If two fractions have the same denominator and different numerators, the fraction with the larger numerator has the larger value. The fraction with the larger numerator represents more of the equal parts. For example, has a greater value than because 7 parts, each part being are larger than 5 parts, each being
Activity 1: Squares and Fractions
Working in pairs or groups of three, students will cut out four squares and arrange them so that equivalent values correspond to form a large square.
Materials
Scissors; reproducible, “Four Squares,” for each pair or group of students.
Procedure
1. Review equivalent fractions and whole numbers expressed as fractions. For example,
2. Hand out copies of the reproducible and explain that students will see four squares, each of which contains fractions and a whole number.
3. Instruct your students to cut out each square.
4. Explain that they should arrange the squares so that the sides that have equivalent fractions are next to each other. Note that the numbers on the squares may not be turned upside down. Remind students that whole numbers may be written as fractions.
Closure
Discuss the positions of the squares with your students.
Answers
Two possible arrangements are shown below.
Activity 2: Balancing Fractions
Working at a Web site, students will virtually drag fraction bars to a scale to determine their relative size.
Materials
Computers with Internet access for students; computer and digital projector for the teacher.
Procedure
1. Instruct your students to go to http://mathplayground.com/Scale_Fractions.html . Explain that they will use a virtual balance scale to compare fractions.
2. Demonstrate how to compare fractions using the virtual balance. For example, dragto the left side of the scale andto the right. The “” is displayed on the scale becauseNext, click “Reset.” Drag fivepieces to the left side of the scale and sevenpieces to the right side to show that
3. Instruct your students to drag other fractions to the scale and write at least five comparisons. They should record their comparisons so that they can share their results with the class at the conclusion of the activity.
Closure
Discuss the comparisons that students made. Discuss any patterns students noticed. For example, they should notice that when the denominators are the same, the larger numerator represents the larger fraction.
Four Squares
Measurement and Data: 3.MD.1
“Solve problems involving measurement and estimation of intervals of time, liquid volumes, and masses of objects.”
1. “Tell and write time to the nearest minute and measure time intervals in minutes. Solve word problems involving addition and subtraction of time intervals in minutes, e.g., by representing the problem on a number line diagram.”
Background
Telling time is an essential skill. By looking at a circular clock students can tell what time it is, what time it will be later, or what time it was a few moments ago. For example, if it is 2:15, students may count by