A tour of how you can add and subtract fractions. Fractions in action A tour of how you can add and subtract fractions.

Objectives Using this program students will be able to add and subtract fractions that do not have common denominators. Students will also learn several key terms for fractions.

Vocabulary Denominator - the bottom number in a fraction. Numerator – the top number in a fraction. Common Denominator – when two or more fractions have the same denominator at the same time. Simplest Form – when a fraction is either a mixed number or simply the numerator is not larger than the denominator.

How to use this tutorial Read through each slide carefully. Remember you may go back and look at a previous slide at any time if you wish. Click on the green buttons to go forward and the red to go back. If there are any questions please ask now and not in the middle of the tutorial.

Rule Number ONE for addition. First we must see if the denominators are the same. 1/3 + 4/5 We must have common denominators in order to add or subtract our fractions. That is a key rule we must follow when adding and subtracting fractions. If they are not we must move on to rule number two. If they are we can move on to rule number three. Are the denominators the same in the problem we are working on? YES NO

Rule Number Two for addition If the denominators are not the same you must find a common number they can both go into. 1/3 + 4/5 In this case 3 and 5 can both go into the number 15. When using the common denominator you must also convert the numerator.

Rule Number Two continued When you expand your fraction to create a common denominator you must multiply by the same number with the numerator. In 1/3 + 4/5 we expanded the denominator to 15 now we must expand the numerators as well. Since the 3 was multiplied by 5 we multiply 1 by 5. Also we multiplied the 5 by 3 to get a denominator of 15 so now we must multiply 4 by 3. Our new fraction looks like this now 5/15 +12/15 This will now take us to rule number three.

Rule Number THREE for addition Once we have common denominators we can now proceed with addition. We will now add the numerators together and stop. In this case it will be 5 + 12. So our new numerator is 17. Our denominator stays the same! We do not add the denominators together. They need to be the same but they are not added together! Our new number is now 17/15 All our fractions need to be reduced and in simplest form. Is your fraction in simplest form? YES NO

Rule Number One for Subtraction First we must see if the denominators are the same. 8/9 - 2/3 Remember we must have common denominators in order to add or subtract fractions that is the rule. If they are not we must move on to rule number two. If they are we can move on to rule number three Do we have common denominators in this problem? YES NO

Rule Number Two for subtraction If the denominators are not the same you must find a common number they can both go into. 8/9 - 2/3 In this case 9 and 3 can both go into the number 9. When using the common denominator you must also convert the numerator.

Rule number Two continued When you expand your fraction to create a common denominator you must multiply by the same number with the numerator. In 8/9 – 2/3 we expanded the denominator to 9 now we must expand the numerators as well. Since the 9 was multiplied by 1 we multiply 8 by 1. Also we multiplied the 3 by 3 to get a denominator of 9 so now we must multiply 2 by 3. Our new fraction looks like this now 8/9 + 6/9 This will now take us to rule number three.

Rule Number Three for subtraction Once we have common denominators we can now proceed with Subtraction. We will now subtract the numerators from each other and stop. In this case it will be 8 - 6. So our new numerator is 2. Our denominator stays the same! We do not add the denominators together. They need to be the same but they are not added together! Our new number is now 2/9! All our fractions need to be reduced and in simplest form. Is your fraction in simplest form? YES NO

Reducing When we reduce fractions into simplest form we are shrinking the numbers within the fraction. We are dividing the numerator and denominator by the same number to make the fraction look smaller. Or when the numerator is larger than the denominator we are creating a mixed number. The numerator can never be larger than the denominator, that is not simplest form. If the numerator is larger we must divide the numerator by the denominator. If there is a remainder, it gets put over the denominator to make our fraction in simplest form.

Pop Quiz #1 Find 2/3 + 1/3 3/6 3/3 1 I do not see the correct answer.

Pop Quiz # 2 Find 3/4 + 2/3 5/7 17/24 5/12 1 and 5/12

Pop Quiz # 3 Find 4/5 – 1/3 3/2 1/5 7/15 I do not see my answer.

Finish Congratulations you have completed the tutorial. You also have answered the pop quiz questions correctly. You are now ready to go off on your own to add and subtract fractions.

Correct!!! You got that one correct! Keep up the good work! Now to Question 2? Now to Question 3? I answered all 3 correctly!

Nice Try The denominators were not the same. Go back and look at the highlighted numbers again. I was adding I was subtracting