Before we begin to add or subtract fractions, we must first understand the meaning of common denominator and how it is found. A common denominator means that the denominators in two or more fractions are the same. The first step to adding and subtracting fractions is to make sure that the denominators are the same. If they are not, we must find their common denominator. This can be done by finding the least common denominator or by multipliying one denominator by the other. To find the LCD, we start by listing the multiplies of our denominators.
I will use the numbers 1/3 and 1/12
3 : 3, 6, 9, 12
12: 12, 24, 36
I then look at these numbers and find the smallest number that they have in common. In this case it is 12, so my common denominator would be 12.
The question that I am to answer is: "How will you explain to your students that when you add or subtract fractions you must have a common denominator but you do not need one with multiplication or divison?"
I think I would simply say that you can't add or subtract two things that are not the same. For example, you can not add an apple and an orange. If you do you will still have 1 apple and 1 orange. You have to have the same type of fruit to be able to add or subtract from them.
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Love the way you made something that may seem hard to students easy. Fractions you would have to cut the apple and orange into equal parts but you need to have the same type of fruit in order to be able to add or subtract that amount from each!!! GOOD JOB
ReplyDeleteThat's great! I think kids will definately understand this. Comparing math to something that they can visualize is always the best way to explain something difficult. i didn't think about it that way until I read your post. Thanks!
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