Students will use dominos to learn about common denominators and fractions.
The use of dominos represents a graphical model for adding unlike fractions. A key concept for students to understand is the common denominator. A common denominator is a common multiple of two or more denominators. A multiple is the lowest number that both (or all) numbers (denominators) can "go into," or be divided into.
In the case of adding or subtracting, unlike fractions, the Least Common Multiple (LCM) needs to be found. The dominos in this activity illustrate the need for a common or matching set of dominos in order to add. That is where we need the common denominator.
As a teacher, you can even explain the use of the term common denominator in everyday speech. For example, the common denominator in the Civil War was hatred of each side for the other. That is what was shared in common--the common cause of the war.
1. Demonstrate a positive learning attitude toward mathematics.
Invitation to Learn
Kids enjoy dominos--whether playing a game or setting them up in a pattern only to tip them over. Students will use dominos to assist them in understanding addition of fractions during this activity.
Have pairs or small groups of students set up two unequal lines of dominos standing on their short end. They can use straight lines or curves--as long as the lines have an unequal amount with a difference of at least three.
When the lines are set up, have students tip them at the same time. What do they notice? Did the shorter line finish first? Of course. They are not even. One line has more than another. Explain that you will use the dominos to add unlike amounts of fractions together.
Another activity using the dominos is done with the numbered sides. With all dominos face down, have a student (in a pair or group) turn over two dominos. On each domino, the smaller number represents the numerator, and the larger number represents the denominator. Have students practice adding and subtracting these fractions on the dominos. Paper and pencil may be needed.
Dominos is a popular game for many families. Many games involve grouping and patterns with a need for number sense and operations. Encourage students to play domino games with families. In the event a student has no access to dominos, at your discretion, they may check out your set.
An ideal assessment method for this activity combines a performance test with a traditional summative test. Students, given a set of problems, model and solve equations using the dominos in this activity. This assessment would indicate conceptual understanding of the process of addition and subtraction of fractions.
Tankersley, K. (1993). Teaching Math Their Way. Educational Leadership, 50, 12-13.
This article follows the development of a methodology of using manipulatives for elementary math that fosters discovery and positive attitudes toward math. It also reflects an increase in testing results in math.
Rust, A. L. (1999). A study of the benefits of math manipulatives versus standard curriculum in the comprehension of mathematical concepts. Knoxville, TN, ERIC 436395.
This dissertation attempted to test first graders using both standard text-book based instruction and the use of manipulatives in math. Conclusions indicated little difference in tested results, though standard curriculum methods did show slightly higher results. However, the article points out that students' enjoyment of the different methods wasn't studied.