Least Common Denominator
In order to find the Least Common Denominator for the fractions 1/2 and 1/3 we must first choose rods which represent both of the denominators. In this case the denominator 2 would be represented by the red rod and the denominator 3 would be represented by the light green rod. Now create a train (rods lined up end-to-end) of red rods and a train of light green rods until they are equal in length. (These trains are also known as multiples). Once you have created trains equal in length, total the number of centimeters in each train. As shown below 3 red rods = 6 cm. and 2 light green rods = 6 cm. Therefore, the common denominator is 6.
Let's try another example:
Find the least common denominator for the fractions 1/4 and 2/3. The denominator 4 will be represented by the purple rod and the 3 will be represented by the light green rod. Now we make our trains.
As shown above 3 purple rods = 12 cm. and 4 light green rods = 12 cm.
Now you try to find the Least Common Denominator using your Cuisenaire
1. 1/6 and 2/3
2. 5/6 and 3/4
3. 1/8 and 1/2
Check your Answers.
|What are Cuisenaire Rods?||Using Cuisenaire Rods to Name a Fraction||Identify the Numerator and Denominator||Least Common Denominator||Adding and Subtracting Fractions|
|Equivalent Fractions||Teacher Notes||Cuisenaire Kids Page||GirlTECH Lessons||More Math Lessons|
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This page was developed through GirlTECH '97, a teacher training and student technology council program sponsored by the Center for Research on Parallel Computation (CRPC), a National Science Foundation-funded Science and Technology Center.
© June 1997 Molly Silha